Add missing newline to end of test_rust.yml

My editor reformatted this file to add a missing newline, and this ended up
breaking the test. The added newline caused there to be a newline in the middle
of the Bazel command. So this change adds the missing newline and fixes up the
Bazel command by using the `>-` syntax to treat this as a multiline string
without adding any newlines.

PiperOrigin-RevId: 558149295

.github/workflows/test_rust.yml

@@ -26,7 +26,7 @@ jobs:
           image: us-docker.pkg.dev/protobuf-build/containers/common/linux/bazel:6.3.0-91a0ac83e968068672bc6001a4d474cfd9a50f1d
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: rust_linux
-          bazel: |
-            test //rust:protobuf_upb_test //rust:protobuf_cpp_test \
-              //rust/test/rust_proto_library_unit_test:rust_upb_aspect_test \
-              //src/google/protobuf/compiler/rust/...
+          bazel: >-
+            test //rust:protobuf_upb_test //rust:protobuf_cpp_test
+            //rust/test/rust_proto_library_unit_test:rust_upb_aspect_test
+            //src/google/protobuf/compiler/rust/...