downgrade ubuntu in order to fix CI

Signed-off-by: Simon L <szaimen@e.mail.de>

.github/workflows/oci.yml

@@ -11,7 +11,7 @@ concurrency:
 
 jobs:
   phpunit-oci:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     strategy:
       matrix:

.github/workflows/s3-primary.yml

@@ -8,7 +8,7 @@ on:
 
 jobs:
   s3-primary-tests-minio:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     strategy:
       # do not stop on another job's failure