git release tags are not signed

It seems that the git tags used to tag MariaDB Server releases are not signed.

For example the recent mariadb-10.6.3 tag by serg and mariadb-10.4.20 by marko don't seem to be signed.

Compare:

noformat
$ git tag -v mariadb-10.5.11
error: mariadb-10.5.11: cannot verify a non-tag object of type commit.
noformat
(from: https://github.com/MariaDB/server/releases/tag/mariadb-10.5.11)

noformat
$ git tag -v debian/1%10.5.11-1
object 916d02055c70372621c463043387e1367e20cb12
type commit
tag debian/1%10.5.11-1
tagger Otto Kekäläinen <otto@debian.org>
noformat
(from: https://salsa.debian.org/mariadb-team/mariadb-10.5/-/tags/debian%2F1%2510.5.11-1)

Signing can be done by adding `-s` to `git tag -s mariadb-10.5.12` when tagging. You could use the same GPG key to sign the tags as is used to sign the tar.gz source releases.

For details see:

• https://docs.github.com/en/github/authenticating-to-github/managing-commit-signature-verification/signing-tags
• https://git-scm.com/book/en/v2/Git-Tools-Signing-Your-Work