chore(ci): Downgrade to Github Actions runner ubuntu-20.04 to avoid SQL Server problems (#545)

Likely related to this
[issue](actions/runner-images#10649).

Author: kagkarlsson

.github/workflows/boot.yml

@@ -2,7 +2,7 @@ name: spring-boot-compatibility
 on: [push]
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         spring-boot: [ '2.5.15', '2.6.15', '2.7.18', '3.0.13', '3.1.10', '3.2.4' ]

.github/workflows/ci.yml

@@ -2,7 +2,7 @@ name: build
 on: [push,pull_request]
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         java: [ '11', '17', '21' ]

.github/workflows/pr-lint.yml

@@ -10,7 +10,7 @@ on:
 jobs:
   main:
     name: Validate PR title
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: amannn/action-semantic-pull-request@v5
         env:

.github/workflows/pr.yml

@@ -2,7 +2,7 @@ name: pull-request-check
 on: [pull_request]
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         java: [ '17' ]

.github/workflows/release.yml

@@ -10,7 +10,7 @@ on:
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     steps:
       - name: Checkout