The installation instructions of a Maven package places the `url` child
of the `repository` node in an extra indentation level. This indentation
is unnecesary since both the `id` and `url` nodes are direct children of
the `repository` node.
This commit removes the unnecessary indentation.
Refs: https://codeberg.org/forgejo/forgejo/pulls/1534
(cherry picked from commit 82f0ddad7b)
(cherry picked from commit 905e546549)
(cherry picked from commit 4e58ab82b7)
(cherry picked from commit 2f207e7deb)
(cherry picked from commit c3552fb2be)
(cherry picked from commit 6c8e4d4fc9)
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