Fix rpm package test workflow

Variables cannot be used to specify the action version. Looks like
we have to wait for an upstream fix to make a node image available
that is compatible with centos7.

.github/workflows/rpm-packages.yaml

@@ -23,14 +23,9 @@ jobs:
         image: [ "centos:centos7", "rockylinux:8", "rockylinux:9" ]
         pg: [ 13, 14, 15, 16 ]
         license: [ "TSL", "Apache"]
-        checkout: [ "v4" ]
         include:
           - license: Apache
             pkg_suffix: "-oss"
-          # centos7 does not have the right versions to support
-          # node20. See https://github.com/actions/runner/issues/2906
-          - image: "centos:centos7"
-            checkout: "v3"
         exclude:
           # PG 16 is not available on centos7
           - image: centos:centos7
@@ -77,7 +72,7 @@ jobs:
       run: |
         rpm -ql timescaledb-2${{ matrix.pkg_suffix }}-postgresql-${{ matrix.pg }}
 
-    - uses: actions/checkout@${{ matrix.checkout }}
+    - uses: actions/checkout@v3
 
     - name: Read versions
       id: versions