Roll external/re2/ 960c86176..73031bbc0 (6 commits)

google/re2@960c861...73031bb

$ git log 960c86176..73031bbc0 --date=short --no-merges --format='%ad %ae %s'
2023-08-22 junyer Reset the Bzlmod compatibility level to 1.
2023-08-17 junyer Clean up `__GNUC__` conditions.
2023-08-11 junyer Add support for `(?<name>expr)`.
2023-08-11 junyer Add a `WORKSPACE.bzlmod` file.
2023-08-11 junyer Migrate to Bzlmod.
2023-08-04 junyer Minor Bazel cleanups.

Created with:
  roll-dep external/re2

DEPS

@@ -12,7 +12,7 @@ vars = {
   # Use protobufs before they gained the dependency on abseil
   'protobuf_revision': 'v21.12',
 
-  're2_revision': '960c861764ff54c9a12ff683ba55ccaad1a8f73b',
+  're2_revision': '73031bbc08cb3e3200497be4a50e37d6f3acc1d0',
   'spirv_headers_revision': 'ae89923fa781650569ca15e5b498a9e4e46ee9c9',
 }