ci: Pin dotnet and codgen workflows to Ubuntu 22.04 (#348)

- Dotnet workflows failing on Ubuntu 24.04 (now ubuntu-latest)

Author: kieran-ryan

.github/workflows/release-nuget.yaml

@@ -8,7 +8,8 @@ on:
 jobs:
   publish-nuget:
     name: Publish package to NuGet.org
-    runs-on: ubuntu-latest
+    # Failing on `ubuntu-24.04` (https://github.com/cucumber/gherkin/issues/349)
+    runs-on: ubuntu-22.04
     environment: Release
     steps:
       - uses: actions/checkout@v4

.github/workflows/test-codegen.yml

@@ -12,7 +12,8 @@ on:
 
 jobs:
   test-codegen:
-    runs-on: ubuntu-latest
+    # Failing on `ubuntu-24.04` (https://github.com/cucumber/gherkin/issues/349)
+    runs-on: ubuntu-22.04
 
     steps:
       - uses: actions/checkout@v4

.github/workflows/test-dotnet.yml

@@ -20,7 +20,8 @@ on:
 
 jobs:
   test-dotnet:
-    runs-on: ubuntu-latest
+    # Failing on `ubuntu-24.04` (https://github.com/cucumber/gherkin/issues/349)
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-dotnet@v4