CSUB-1374: Tell gitleaks to scan only commits in the current PR

[atodorov]

Description of proposed changes

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Practical tips for PR review & merge:

• All GitHub Actions report PASS
• Newly added code/functions have unit tests
  • Coverage tools report all newly added lines as covered
  • The positive scenario is exercised
  • Negative scenarios are exercised, e.g. assert on all possible errors
  • Assert on events triggered if applicable
  • Assert on changes made to storage if applicable
• Modified behavior/functions - try to make sure above test items are covered
• Integration tests are added if applicable/needed

[github-actions]

For full LLVM coverage report click here!

[atodorov]

TEST RESULTS:

1. With a685ce5 included then MegaLinter + gitleaks reports FAIL, as expected, see https://github.com/gluwa/creditcoin3/actions/runs/11934332498/job/33263220586?pr=529. Note: this is the commit which initially introduced this issue into the repository, Handle polkadot forks #483 (comment).

2. Without the commit mentioned above, MegaLinter + gitleaks reports PASS, https://github.com/gluwa/creditcoin3/actions/runs/11934233925/job/33262918284.

These results should be evidence that gitleaks is looking only into the commits from the current PR that MegaLinter is operating upon, instead of all commits, from all branches currently present in the repository!

[beqaabu]

LGTM

unrelated to this pr but the ci is failing on deploying contracts with hardhat, see https://github.com/gluwa/creditcoin3/actions/runs/11934458057/job/33264244676?pr=529

[atodorov]

unrelated to this pr but the ci is failing on deploying contracts with hardhat, see https://github.com/gluwa/creditcoin3/actions/runs/11934458057/job/33264244676?pr=529

Yes, I am aware of this. Will be resolved in https://gluwa.atlassian.net/browse/CSUB-1368