Set GZ_TOOLS_VER to 2 for consistency with rest of Garden and Harmonic libraries

[traversaro]

🦟 Bug fix

All other Garden and Harmonic libraries install the auto-completion to share/gz/gz2.completion.d/, while gz-tools install them to share/gz/gz1.completion.d/, I guess this was just a typo/leftover.

Summary

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #391 (36c5ba9) into gz-msgs9 (ca9d66c) will not change coverage.
The diff coverage is n/a.

❗ Current head 36c5ba9 differs from pull request most recent head 690d2a6. Consider uploading reports for the commit 690d2a6 to get more accurate results

@@            Coverage Diff            @@
##           gz-msgs9     #391   +/-   ##
=========================================
  Coverage     95.57%   95.57%           
=========================================
  Files            10       10           
  Lines          1062     1062           
=========================================
  Hits           1015     1015           
  Misses           47       47