Bump iffy/install-nim from 5.0.6 to 5.0.8 (#2943)

Bumps [iffy/install-nim](https://github.com/iffy/install-nim) from 5.0.6 to 5.0.8.
- [Release notes](https://github.com/iffy/install-nim/releases)
- [Changelog](https://github.com/iffy/install-nim/blob/master/CHANGELOG.md)
- [Commits](iffy/install-nim@v5.0.6...v5.0.8)

---
updated-dependencies:
- dependency-name: iffy/install-nim
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

.github/workflows/testpr.yml

@@ -8,7 +8,7 @@ jobs:
         with:
           fetch-depth: 0
           ref: ${{ github.event.pull_request.head.sha }}
-      - uses: iffy/[email protected].6
+      - uses: iffy/[email protected].8
         with:
           version: stable
       - run: ./getmergebase.sh

.github/workflows/testpush.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: iffy/[email protected].6
+      - uses: iffy/[email protected].8
         with:
           version: stable
       - run: nim c -d:ssl -r -d:release package_scanner.nim packages.json