Deprecates RUN_THIS.py in favor of manually doin' it (#3930)

RUN_THIS.py

@@ -1,18 +0,0 @@
-#!/usr/bin/env python3
-
-# Import future so people on py2 still get the clear error that they need to upgrade.
-from __future__ import print_function
-import sys
-import subprocess
-
-IS_WINDOWS = sys.platform in ("win32", "cygwin")
-
-version = sys.version_info
-if version.major < 3 or (version.major == 3 and version.minor < 5):
-    print("ERROR: You need at least Python 3.5 to build SS14.")
-    sys.exit(1)
-
-if IS_WINDOWS:
-    subprocess.run(["py", "-3", "git_helper.py"], cwd="BuildChecker")
-else:
-    subprocess.run(["python3", "git_helper.py"], cwd="BuildChecker")