chore(deps): update dependency buildifier_prebuilt to v7 (#534)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

WORKSPACE.bazel

@@ -159,10 +159,10 @@ http_archive(
 
 http_archive(
     name = "buildifier_prebuilt",
-    sha256 = "72b5bb0853aac597cce6482ee6c62513318e7f2c0050bc7c319d75d03d8a3875",
-    strip_prefix = "buildifier-prebuilt-6.3.3",
+    sha256 = "7f85b688a4b558e2d9099340cfb510ba7179f829454fba842370bccffb67d6cc",
+    strip_prefix = "buildifier-prebuilt-7.3.1",
     urls = [
-        "http://github.com/keith/buildifier-prebuilt/archive/6.3.3.tar.gz",
+        "http://github.com/keith/buildifier-prebuilt/archive/7.3.1.tar.gz",
     ],
 )