Use Swiftlang's github action for unit tests (#614)

Remove a dependency on Swift NIO's GitHub workflows and use Swiftlang's
github action for unit tests instead

---------

Co-authored-by: Sebastien Stormacq <stormacq@amazon.lu>

Author: sebsto

.github/workflows/pull_request.yml

@@ -22,12 +22,13 @@ jobs:
 
   unit-tests:
     name: Unit tests
-    uses: apple/swift-nio/.github/workflows/unit_tests.yml@main
+    uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
     with:
-      linux_5_9_enabled: false
-      linux_5_10_enabled: false
-      linux_nightly_next_arguments_override: "--explicit-target-dependency-import-check error"
-      linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error"
+      enable_windows_checks: false
+      linux_exclude_swift_versions: "[{\"swift_version\": \"5.9\"}, {\"swift_version\": \"5.10\"}]"
+      swift_flags: "--explicit-target-dependency-import-check error"
+      swift_nightly_flags: "--explicit-target-dependency-import-check error"
+      enable_linux_static_sdk_build: true
 
   integration-tests:
     name: Integration Tests
@@ -43,10 +44,6 @@ jobs:
       archive_plugin_examples: "[ 'HelloWorld', 'ResourcesPackaging' ]"
       archive_plugin_enabled: true
 
-  swift-6-language-mode:
-    name: Swift 6 Language Mode
-    uses: apple/swift-nio/.github/workflows/swift_6_language_mode.yml@main
-
   semver-label-check:
     name: Semantic Version label check
     runs-on: ubuntu-latest
@@ -58,11 +55,3 @@ jobs:
           persist-credentials: false
       - name: Check for Semantic Version label
         uses: apple/swift-nio/.github/actions/pull_request_semver_label_checker@main
-
-  musl:
-    name: Linux Static SDK (musl) Test
-    uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
-    with:
-      enable_linux_checks: false
-      enable_linux_static_sdk_build: true
-      enable_windows_checks: false