disable integration tests on Swift < 6.0

Author: sebsto

.github/workflows/pull_request.yml

@@ -29,8 +29,11 @@ jobs:
         # Workaround https://github.com/nektos/act/issues/1875
         uses: apple/swift-nio/.github/workflows/swift_matrix.yml@main
         with:
-          name: "Integration tests"
-          matrix_linux_command: "./scripts/integration_tests.sh"
+            name: "Integration tests"
+            matrix_linux_command: "./scripts/integration_tests.sh"
+            linux_5_8_enabled: false
+            linux_5_9_enabled: false
+            linux_5_10_enabled: false
 
     swift-6-language-mode:
         name: Swift 6 Language Mode