build(deps): bump sigstore/cosign-installer from 3.8.0 to 3.8.1 (linkerd#487)

Bumps [sigstore/cosign-installer](https://github.com/sigstore/cosign-installer) from 3.8.0 to 3.8.1.
- [Release notes](https://github.com/sigstore/cosign-installer/releases)
- [Commits](sigstore/cosign-installer@c56c2d3...d7d6bc7)

---
updated-dependencies:
- dependency-name: sigstore/cosign-installer
  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>

Author: dependabot[bot]

.github/workflows/release-cni-plugin.yml

@@ -66,7 +66,7 @@ jobs:
                   --platform linux/amd64,linux/arm64,linux/arm/v7 \
                   --output type=registry
       - if: needs.meta.outputs.mode == 'release'
-        uses: sigstore/cosign-installer@c56c2d3e59e4281cc41dea2217323ba5694b171e
+        uses: sigstore/cosign-installer@d7d6bc7722e3daa8354c50bcb52f4837da5e9b6a
       - if: needs.meta.outputs.mode == 'release'
         run: cosign sign -y "${{ needs.meta.outputs.repo }}:${{ needs.meta.outputs.version }}"
         env:

.github/workflows/release-proxy-init.yml

@@ -66,7 +66,7 @@ jobs:
                   --platform linux/amd64,linux/arm64,linux/arm/v7 \
                   --output type=registry
       - if: needs.meta.outputs.mode == 'release'
-        uses: sigstore/cosign-installer@c56c2d3e59e4281cc41dea2217323ba5694b171e
+        uses: sigstore/cosign-installer@d7d6bc7722e3daa8354c50bcb52f4837da5e9b6a
       - if: needs.meta.outputs.mode == 'release'
         run: cosign sign -y "${{ needs.meta.outputs.repo }}:${{ needs.meta.outputs.version }}"
         env: