Use explicit ubuntu version instead of ubuntu-latest (#1078)

`ubuntu-latest` is an alias/pointer which over time changes and points at newer ubuntu images. Different ubuntu images have different compiler versions installed and newer images drop older compiler versions. So to keep the CI builds running successfully it's better to use explicit version requirements.

Signed-off-by: Neil Henderson <[email protected]>

Author: bluetarpmedia

Diff for: .github/workflows/regression-tests.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest]
+        os: [ubuntu-22.04]
         compiler: [g++-10, clang++-15]
         include:
           - os: ubuntu-24.04