[clang][deps] Specify Python 3 in shebang

Some build bots don't like plain `python` in the shebang: https://lab.llvm.org/buildbot/#/builders/139/builds/4147.

diff --git a/clang/utils/module-deps-to-rsp.py b/clang/utils/module-deps-to-rsp.py
index 56402bf..7b0534d 100755 (executable)
--- a/clang/utils/module-deps-to-rsp.py
+++ b/clang/utils/module-deps-to-rsp.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Converts clang-scan-deps output into response files.
 #   * For modules, arguments in the resulting response file are enough to build a PCM.