Correct typo in build artifact comment workflow.

.github/workflows/build_artifact_comment.yml

@@ -81,7 +81,7 @@ jobs:
             });
             const PREFIX = "## Plugin ready!";
             let body = PREFIX + "\n\n" +
-                "A test version of this PR are available for testing [here](https://github.com/" + context.repo.owner + "/" + context.repo.repo + "/suites/" +  context.payload.workflow_run.check_suite_id + "/artifacts/${{steps.download_artifact.outputs.artifact_id}}).";
+                "A test version of this PR is available for testing [here](https://github.com/" + context.repo.owner + "/" + context.repo.repo + "/suites/" +  context.payload.workflow_run.check_suite_id + "/artifacts/${{steps.download_artifact.outputs.artifact_id}}).";
             body += "\n\n*(Built from commit " + git_sha + ")*";
 
             const winBuildComment = prComments.data?.find(c => c.body.startsWith(PREFIX));