fix: add the .pub extension to the git user.signingkey

see: https://docs.github.com/en/authentication/managing-commit-signature-verification/telling-git-about-your-signing-key#telling-git-about-your-ssh-key

tasks/git.yml

@@ -3,6 +3,6 @@
     git config --global user.name "{{ git_name }}"
     git config --global user.email "{{ git_email }}"
     git config --global gpg.format ssh
-    git config --global user.signingkey ~/.ssh/{{ git_ssh_key }}
+    git config --global user.signingkey ~/.ssh/{{ git_ssh_key }}.pub
     git config --global pull.rebase false
-    git config --global init.defaultBranch main
+    git config --global init.defaultBranch main