Fix spacing in new contributor welcome message (#28958)

* Fix spacing in new contributor welcome message

After committing this new welcome message #28118, I noticed a few minor spacing issues in the implementation. This PR is a very simple fix to get proper spacing in place!

* update test

Co-authored-by: ntsekouras <ntsekouras@outlook.com>

packages/project-management-automation/lib/tasks/first-time-contributor-label/index.js

@@ -58,7 +58,7 @@ async function firstTimeContributorLabel( payload, octokit ) {
 		body:
 			':wave: Thanks for your first Pull Request and for helping build the future of Gutenberg and WordPress, @' +
 			author +
-			"!. In case you missed it, we'd love to have you join us in our [Slack community](https://make.wordpress.org/chat/)," +
+			"! In case you missed it, we'd love to have you join us in our [Slack community](https://make.wordpress.org/chat/), " +
 			'where we hold [regularly weekly meetings](https://make.wordpress.org/core/tag/core-editor-summary/) open to anyone to coordinate with each other.\n\n' +
 			'If you want to learn more about WordPress development in general, check out the [Core Handbook](https://make.wordpress.org/core/handbook/) full of helpful information.',
 	} );

packages/project-management-automation/lib/tasks/first-time-contributor-label/test/index.js

@@ -64,8 +64,8 @@ describe( 'firstTimeContributorLabel', () => {
 
 		const expectedComment =
 			':wave: Thanks for your first Pull Request and for helping build the future of Gutenberg and WordPress, @ghost' +
-			"!. In case you missed it, we'd love to have you join us in our [Slack community](https://make.wordpress.org/chat/)," +
-			'where we hold [regularly weekly meetings](https://make.wordpress.org/core/tag/core-editor-summary/) open to anyone to coordinate with each other.\n\n' +
+			"! In case you missed it, we'd love to have you join us in our [Slack community](https://make.wordpress.org/chat/)," +
+			' where we hold [regularly weekly meetings](https://make.wordpress.org/core/tag/core-editor-summary/) open to anyone to coordinate with each other.\n\n' +
 			'If you want to learn more about WordPress development in general, check out the [Core Handbook](https://make.wordpress.org/core/handbook/) full of helpful information.';
 
 		await firstTimeContributorLabel( payload, octokit );