release-candidate: pin upload-artifact to specific version.

.github/workflows/release-candidate.yml

@@ -17,7 +17,7 @@ jobs:
           mkdir linux-release-candidate
           cp linux/artifacts/*.deb linux-release-candidate/
           cp linux/artifacts/*.tar.gz linux-release-candidate/
-    - uses: actions/upload-artifact@master
+    - uses: actions/upload-artifact@v2
       with:
         name: linux-release-candidate
         path: linux-release-candidate
@@ -88,7 +88,7 @@ jobs:
           copy windows\pandoc-%VERSION%-${{ matrix.versions.osarch }}-UNSIGNED.msi windows-release-candidate
           copy windows\pandoc-%VERSION%-${{ matrix.versions.osarch }}.zip windows-release-candidate
           copy windows\Makefile windows-release-candidate
-    - uses: actions/upload-artifact@master
+    - uses: actions/upload-artifact@v2
       with:
         name: windows-release-candidate
         path: windows-release-candidate
@@ -134,7 +134,7 @@ jobs:
           sed -e "s/PANDOCVERSION/${VERSION}/" macos/distribution.xml.in > ${ARTIFACTS}/distribution.xml
           cp macos/Makefile ${ARTIFACTS}/
           echo ${VERSION} > ${ARTIFACTS}/version.txt
-    - uses: actions/upload-artifact@master
+    - uses: actions/upload-artifact@v2
       with:
         name: macos-release-candidate
         path: macos-release-candidate