gplugin/gplugin

Bump the minimum meson to 0.61.0 and clean up some warnings

2022-04-18, Gary Kramlich
55291fd09e7d
Bump the minimum meson to 0.61.0 and clean up some warnings

Testing Done:
Compiled.

Reviewed at https://reviews.imfreedom.org/r/1350/
<?xml version="1.0" encoding="UTF-8"?>
<gresources>
<gresource prefix="/org/imfreedom/keep/gplugin/gplugin-gtk/">
<file compressed="true">plugin-info.ui</file>
</gresource>
</gresources>