Update submodule to latest `release-branch.go1.21` in `microsoft/release-branch.go1.21`#1103

Merged

dagood merged 2 commits intomicrosoft/release-branch.go1.21from dev/auto-sync/microsoft/release-branch.go1.21

Jan 11, 2024

+1,302-421

Commits on Jan 9, 2024

Update submodule to latest release-branch.go1.21 (cc85462b): [release-branch.go1.21] go1.21.6
microsoft-golang-bot
committed

Commits on Jan 10, 2024

Update backends to support NewGCMTLS13
dagood
committed