Fix pushing tags: overwrite if tag already exists

[tortila]

Signed-off-by: Oliwia Zaremba oliwia.zaremba@zalando.de

No functional changes!

Post-fix to #50

Description

This PR aims to fix the error on Travis (as seen here) where git tag fails because: fatal: tag 'v1.2.2' already exists

Types of Changes

• Configuration change

Review

Reviewers' checklist:

• If this PR implements new flows or changes existing ones, are there
  good tests for these flows?
  If this PR rather removes flows, are the obsolete tests removed as well?
• Is the documentation still up-to-date and exhaustive? This covers both
  technical (in source files) and functional (under docs/) documentation.
• Is the changelog updated?
• Does the new version number correspond to the actual changes from this PR?
  In doubt, refer to https://semver.org.

After this PR

Check if build on Travis passes and the tag v1.2.3 is created and visible on GitHub.

[zincr]

🤖 zincr found 0 problems , 0 warnings

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