Travis cache update fails on windows machines

caching

#1

Sometimes windows machine tasks fails on the cache update stage with the “No output has been received in the last 10m0s” error like following:

store build cache
Running casher in bash
changes detected (content changed, file is created, or file is deleted):
C:\Users	ravis\.carginchanges detected, packing new archive
No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#Build-times-out-because-no-output-was-received
The build has been terminated

https://travis-ci.com/exonum/exonum-merkledb/jobs/176709836