[DL]String additions to 'gnome-builder.gnome-builder-43'

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There have been following string additions to module 'gnome-builder.gnome-builder-43':

+ "Keys may not start with a number"
    + "Keys may only contain alpha-numerics or underline."
    + "Use KEY=VALUE to set an environment variable"

Note that this doesn't directly indicate a string freeze break, but it
might be worth investigating.
https://gitlab.gnome.org/GNOME/gnome-builder/commits/gnome-builder-43