Upgrade rust/crates/regex-syntax to 0.6.23 am: 6f928bfd50 am: fa99334ded am: 36d9b48fbe

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/regex-syntax/+/1663040

Change-Id: Iff21e6a2a8bcf7715c0430ca718d9b38fd0ad4cd