Add exclusion for /vendor directory in zip build. (#2106)

The composer archive previously included the /vendor directory where the
.gitignore excluded it. This adjusts the composer archive exclude array
to omit the /vendor directory from the zip generation.

composer.json

@@ -11,12 +11,12 @@
 		"exclude": [
 			"!/assets",
 			"!/languages",
-			"!/vendor",
 			"!/style.css",
 			"!/style-rtl.css",
 			"/assets/css/sass",
 			"/assets/css/**/*.scss",
 			"/e2e",
+			"/vendor",
 			"composer.json",
 			"composer.lock",
 			"package.json",
@@ -73,4 +73,4 @@
 			"composer/installers": true
 		}
 	}
-}
+}