Bumped version to 0.7.0

[tadani3]

This pull request updates the project version from 0.6.3 to 0.7.0 in the VERSION file as part of the release process for onnxscript.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.48%. Comparing base (c6e8ec6) to head (14e8c56).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2894   +/-   ##
=======================================
  Coverage   72.48%   72.48%           
=======================================
  Files         241      241           
  Lines       29915    29915           
  Branches     2935     2935           
=======================================
  Hits        21684    21684           
  Misses       7233     7233           
  Partials      998      998           

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