github-ci: replace failing CentOS 8 by AlmaLinux 8.4

(cherry picked from commit 6c24093)

.github/workflows/builds.yml

@@ -139,10 +139,10 @@ jobs:
           name: prep
           path: .
 
-  centos-8:
-    name: CentOS 8
+  alma-8:
+    name: AlmaLinux 8
     runs-on: ubuntu-latest
-    container: centos:8
+    container: almalinux:8.4
     needs: [prepare-deps, prepare-cbindgen]
     steps:
       # Cache Rust stuff.
@@ -254,7 +254,7 @@ jobs:
     name: CentOS 7
     runs-on: ubuntu-latest
     container: centos:7
-    needs: centos-8
+    needs: [prepare-deps, alma-8]
     steps:
       - name: Install system dependencies
         run: |
@@ -593,7 +593,7 @@ jobs:
     name: Ubuntu 20.04 (unsupported rust)
     runs-on: ubuntu-latest
     container: ubuntu:20.04
-    needs: centos-8
+    needs: alma-8
     steps:
       - name: Install dependencies
         run: |
@@ -878,7 +878,7 @@ jobs:
     name: Ubuntu 20.04 (MSRV)
     runs-on: ubuntu-latest
     container: ubuntu:20.04
-    needs: centos-8
+    needs: alma-8
     steps:
       - name: Install dependencies
         run: |