Bump gap-actions/build-pkg from 1 to 2 (#25)

Bumps [gap-actions/build-pkg](https://github.com/gap-actions/build-pkg) from 1 to 2.
- [Commits](gap-actions/build-pkg@v1...v2)

---
updated-dependencies:
- dependency-name: gap-actions/build-pkg
  dependency-version: '2'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/CI.yml

@@ -36,6 +36,6 @@ jobs:
       - uses: gap-actions/setup-gap@v3
         with:
           gap-version: ${{ matrix.gap-version }}
-      - uses: gap-actions/build-pkg@v1
+      - uses: gap-actions/build-pkg@v2
       - uses: gap-actions/run-pkg-tests@v3
       - uses: ./this-action/