ci: add diff report

[vladopajic]

No description provided.

[github-actions]

go-test-coverage report:

File coverage threshold (100%) satisfied:	FAIL
  below threshold:				coverage:	threshold:
  pkg/testcoverage/badge.go			48.5% (16/33)	100%
  pkg/testcoverage/badgestorer/github.go	94.1% (16/17)	100%

Total coverage threshold (100%) satisfied:	FAIL
Total test coverage: 96.4% (480/498)

Current tests coverage has changed with 18 lines missing coverage.
  file:						uncovered:	current coverage:	base coverage:
  pkg/testcoverage/badge.go			 17		48.5% (16/33)		100% (33/33)
  pkg/testcoverage/badgestorer/github.go	  1		94.1% (16/17)		100% (17/17)