build(deps): bump r-lib/actions from 2.8.6 to 2.8.7

PR-URL #2226

Bumps [r-lib/actions](https://github.com/r-lib/actions) from 2.8.6 to 2.8.7.
- [Release notes](https://github.com/r-lib/actions/releases)
- [Changelog](https://github.com/r-lib/actions/blob/v2-branch/NEWS.md)
- [Commits](r-lib/actions@7171bbd...b7e68d6)

---
updated-dependencies:
- dependency-name: r-lib/actions
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>

Author: dependabot[bot]

.github/workflows/lint_changed_files.yml

@@ -248,7 +248,7 @@ jobs:
       - name: 'Setup R'
         if: ( success() || failure() ) && steps.check-r-files.outputs.files != ''
         # Pin action to full length commit SHA
-        uses: r-lib/actions/setup-r@7171bbdc297d5a76f04914d60e5c8144991e3011 # v2.6.4
+        uses: r-lib/actions/setup-r@b7e68d63e51bdf225997973e2add36d551f60f02 # v2.6.4
         with:
           r-version: '3.5.3'
 

.github/workflows/lint_random_files.yml

@@ -317,7 +317,7 @@ jobs:
       - name: 'Setup R'
         if: ( github.event.inputs.r != 'false' ) && ( success() || failure() )
         # Pin action to full length commit SHA
-        uses: r-lib/actions/setup-r@7171bbdc297d5a76f04914d60e5c8144991e3011 # v2.6.4
+        uses: r-lib/actions/setup-r@b7e68d63e51bdf225997973e2add36d551f60f02 # v2.6.4
         with:
           r-version: '4.3.3'