[CI] Enable Linux nightly main on PRs

Author: czechboy0

.github/workflows/pull_request.yml

@@ -19,12 +19,11 @@ jobs:
       linux_5_10_arguments_override: "--explicit-target-dependency-import-check error"
       linux_6_0_arguments_override: "--explicit-target-dependency-import-check error"
       linux_nightly_6_0_arguments_override: "--explicit-target-dependency-import-check error"
-      linux_nightly_main_enabled: false
+      linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error"
 
   integration-test:
     name: Integration test
     uses: apple/swift-nio/.github/workflows/swift_matrix.yml@main
     with:
       name: "Integration test"
       matrix_linux_command: "apt-get update -yq && apt-get install -yq jq && ./scripts/run-integration-test.sh"
-      matrix_linux_nightly_main_enabled: false