CI: Don't pin msys2 packages to a specific version at all
Similar to !286 (merged), but more so: just use the package names, ignoring their version numbers completely.
pcre2 is not strictly needed at the moment, but it'll be a dependency for GLib >= 2.73.x (older versions used pcre). For a bit of future-proofing, download both pcre and pcre2.
Edited by Simon McVittie