[Snyk] Security upgrade nginx from latest to 1.21#2

snyk-bot wants to merge 1 commit intomasterbaby636/bitcoinabc.org:masterfrom

snyk-fix-2920ea48866889dabcadf2f8f9971b84baby636/bitcoinabc.org:snyk-fix-2920ea48866889dabcadf2f8f9971b84Copy head branch name to clipboard