[upstream_utils] Remove git version from upstream patches (#4351)

This reduces commit noise when other git versions are used. The version
was removed by passing `--no-signature` to `git format-patch` which is
now documented in the readme.

upstream_utils/llvm_patches/0013-Extra-collections-features.patch

@@ -160,6 +160,3 @@ index 3abeed3dac21..27bba0ca2f06 100644
  raw_ostream::~raw_ostream() {
    // raw_ostream's subclasses should take care to flush the buffer
    // in their destructors.
--- 
-2.20.1.windows.1
-