Bump sigstore/cosign-installer from 2.5.1 to 2.6.0 (#407)

Author: dependabot[bot]

.github/workflows/build.yaml

@@ -182,7 +182,7 @@ jobs:
       # https://github.com/sigstore/cosign-installer
       - name: Install cosign
         if: github.event_name != 'pull_request'
-        uses: sigstore/cosign-installer@v2.5.1
+        uses: sigstore/cosign-installer@v2.6.0
 
 
       # Workaround: https://github.com/docker/build-push-action/issues/461
@@ -291,7 +291,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Install cosign
-        uses: sigstore/cosign-installer@v2.5.1
+        uses: sigstore/cosign-installer@v2.6.0
       - name: Download executables
         uses: actions/download-artifact@v3
         with: