actions: remove RPM build step

It seems to be broken, and I'm not sure if anyone's actually using it.

.github/workflows/release-artifacts.yml

@@ -73,27 +73,10 @@ jobs:
         name: packaged-deb
         path: target/debian/*.deb
 
-  build-rpm:
-    name: 'Build RPM packages'
-    continue-on-error: true
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        distros: ['fedora:32', 'fedora:33', 'centos:8']
-    steps:
-    - uses: actions/checkout@v2
-    - name: Build RPMs
-      run: rpm/build-package.sh ${{ matrix.distros }}
-    - name: Save RPMs
-      uses: actions/upload-artifact@v2
-      with:
-        name: packaged-rpm
-        path: target/rpm/*.rpm
-
   release:
     name: 'Release packages'
     runs-on: ubuntu-latest
-    needs: [build-deb, build-rpm]
+    needs: [build-deb]
     steps:
     - name: Get artifacts
       uses: actions/download-artifact@v2