Unset once saved

Author: lildude

script/codespaces-post-start

@@ -24,6 +24,7 @@ fi
 if [ ! -f "${HOME}/.ssh/git_signing_ed25519" ]; then
   # Takes this from my Codespaces secrets config on GitHub
   echo "$GIT_SIGNING_KEY" > "${HOME}/.ssh/git_signing_ed25519"
+  unset GIT_SIGNING_KEY
   chmod 600 "${HOME}/.ssh/git_signing_ed25519"
 fi