"sudo apt update" failure in linux

Below is the party of travis.yml

language: php
php: 7.2
group: stable
dist: trusty
os: linux
sudo: required

cache:
  directories:
    - $HOME/.composer/cache/files

branches:
  only:
    - master
    - /^development.*/

services:
  - redis-server

addons:
  apt:
    sources:
      - mysql-5.7-trusty
    packages:
      - mysql-server

before_install:
  - cat /etc/lsb-release
  - printf "\n" | sudo LC_ALL=C.UTF-8 add-apt-repository -y ppa:ondrej/php
  - sudo apt update
  - sudo apt install -y php7.2-bcmath --fix-missing
  - pecl install protobuf

Got error like this:

$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu 14.04.5 LTS"
before_install.2
1.50s$ printf "\n" | sudo LC_ALL=C.UTF-8 add-apt-repository -y ppa:ondrej/php
gpg: keyring `/tmp/tmpa2higr52/secring.gpg' created
gpg: keyring `/tmp/tmpa2higr52/pubring.gpg' created
gpg: requesting key E5267A6C from hkp server keyserver.ubuntu.com
gpg: /tmp/tmpa2higr52/trustdb.gpg: trustdb created
gpg: key E5267A6C: public key "Launchpad PPA for Ondřej Surý" imported
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)
OK
4.52s$ sudo apt update
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
Hit:1 http://dl.hhvm.com/ubuntu trusty InRelease
Ign:2 http://repo.mongodb.org/apt/ubuntu trusty/mongodb-org/3.4 InRelease
Hit:3 http://repo.mysql.com/apt/ubuntu trusty InRelease
Hit:4 http://repo.mongodb.org/apt/ubuntu trusty/mongodb-org/3.4 Release
Hit:5 http://apt.postgresql.org/pub/repos/apt trusty-pgdg InRelease
Ign:6 http://us-east-1.ec2.archive.ubuntu.com/ubuntu trusty InRelease
Hit:9 http://us-east-1.ec2.archive.ubuntu.com/ubuntu trusty-updates InRelease
Hit:10 http://us-east-1.ec2.archive.ubuntu.com/ubuntu trusty-backports InRelease
Hit:11 http://us-east-1.ec2.archive.ubuntu.com/ubuntu trusty Release
Get:7 http://dl.bintray.com/apache/cassandra 39x InRelease [3,168 B]
Hit:12 http://ppa.launchpad.net/chris-lea/redis-server/ubuntu trusty InRelease
Hit:14 https://download.docker.com/linux/ubuntu trusty InRelease
Ign:8 http://toolbelt.heroku.com/ubuntu ./ InRelease
Ign:15 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:17 http://dl.google.com/linux/chrome/deb stable Release
Hit:16 http://toolbelt.heroku.com/ubuntu ./ Release
Ign:18 http://ppa.launchpad.net/couchdb/stable/ubuntu trusty InRelease
Hit:20 http://ppa.launchpad.net/git-core/ppa/ubuntu trusty InRelease
Get:22 http://ppa.launchpad.net/ondrej/php/ubuntu trusty InRelease [20.9 kB]
Hit:23 http://security.ubuntu.com/ubuntu trusty-security InRelease
Hit:25 https://packagecloud.io/computology/apt-backport/ubuntu trusty InRelease
Hit:26 http://ppa.launchpad.net/openjdk-r/ppa/ubuntu trusty InRelease
Hit:27 http://ppa.launchpad.net/pollinate/ppa/ubuntu trusty InRelease
Get:28 https://packagecloud.io/github/git-lfs/ubuntu trusty InRelease [23.2 kB]
Err:28 https://packagecloud.io/github/git-lfs/ubuntu trusty InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6B05F25D762E3157
Hit:29 http://ppa.launchpad.net/webupd8team/java/ubuntu trusty InRelease
Hit:30 https://packagecloud.io/rabbitmq/rabbitmq-server/ubuntu trusty InRelease
Hit:31 http://ppa.launchpad.net/couchdb/stable/ubuntu trusty Release
Get:33 http://ppa.launchpad.net/ondrej/php/ubuntu trusty/main amd64 Packages [67.2 kB]
Get:34 http://ppa.launchpad.net/ondrej/php/ubuntu trusty/main i386 Packages [67.2 kB]
Get:35 http://ppa.launchpad.net/ondrej/php/ubuntu trusty/main Translation-en [43.6 kB]
Reading package lists...
W: GPG error: https://packagecloud.io/github/git-lfs/ubuntu trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6B05F25D762E3157
E: The repository 'https://packagecloud.io/github/git-lfs/ubuntu trusty InRelease' is not signed.
W: http://ppa.launchpad.net/couchdb/stable/ubuntu/dists/trusty/Release.gpg: Signature by key 15866BAFD9BCC4F3C1E0DFC7D69548E1C17EAB57 uses weak digest algorithm (SHA1)
The command "sudo apt update" failed and exited with 100 during .
Your build has been stopped.

We are also seeing this error:

$ sudo apt-get update -qq

W: GPG error: https://packagecloud.io/github/git-lfs/ubuntu trusty InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 6B05F25D762E3157

W: The repository ‘https://packagecloud.io/github/git-lfs/ubuntu trusty InRelease’ is not signed.

W: There is no public key available for the following key IDs:

6B05F25D762E3157

The MySQL repository is broken upstream. See Can't install MySQL 5.7 on Ubuntu Trusty.

If it helps, you’ll be able to use MySQL 5.7 on our Xenial image. To do so, please remove

addons:
  apt:
    sources:
      - mysql-5.7-trusty
    packages:
      - mysql-server

and add

dist: xenial
services:
  - redis-server
  - mysql

to your .travis.yml file.

Please let us know how it goes.

Thanks!