CI: Run tests on ubuntu-latest

.github/workflows/multiarch.yaml tests started to fail in glib2:

    Exec failed with: Failed to close file descriptor for child process (Operation not permitted)

That's the 2-year-old GitHub bug
<actions/runner-images#3812>. Some other
projects which run ubuntu-latest reported that the bug is already
fixed. We used ubuntu-20.04. ubuntu-latest is ubuntu-22.04 now. Try that.

.github/workflows/formatters.yaml

@@ -4,7 +4,7 @@ on: push
 jobs:
   autoformat:
     name: Auto-format code
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout code
         uses: actions/checkout@v2

.github/workflows/multiarch.yaml

@@ -3,11 +3,11 @@ on: [push, pull_request]
 
 jobs:
   multiarch:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     name: ${{ matrix.distro }} on ${{ matrix.arch }}
     continue-on-error: true
 
-    # Run steps on a matrix of 3 arch/distro combinations
+    # Run steps on a matrix of 2 arch/distro combinations
     strategy:
       matrix:
         include:

.github/workflows/release.yaml

@@ -6,7 +6,7 @@ on:
 jobs:
   docs:
     name: Publish Documentation
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     continue-on-error: false
     if: github.repository == 'fedora-modularity/libmodulemd'
     steps:

.github/workflows/upstreamed.yaml

@@ -6,7 +6,7 @@ on:
 jobs:
   static_analysis:
     name: Static Analysis
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     if: github.repository == 'fedora-modularity/libmodulemd'
     steps:
       - name: Checkout code
@@ -20,7 +20,7 @@ jobs:
 
   docs:
     name: Publish Documentation
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     continue-on-error: false
     if: github.repository == 'fedora-modularity/libmodulemd'
     steps: