Fix build task matcher

This is a pattern so we need to escape special regepx chars like `.`

.vscode/tasks.json

@@ -54,7 +54,7 @@
 					"message": 3
 				},
 				"background": {
-					"beginsPattern": "Starting compilation...",
+					"beginsPattern": "Starting compilation\\.\\.\\.",
 					"endsPattern": "Finished compilation with"
 				}
 			}