Meson: capture the output of the custom target

Previously meson would withhold the stdout output, and only
print it once the job was finished. This was a bit problematic
with the current way we wire cargo into meson, cause you have
no output of whats going on till then causing a degraded UX.

With this change output is printed directly to stdout and
behaves as expected.

https://mesonbuild.com/Reference-manual.html#custom_target

meson.build

@@ -53,6 +53,7 @@ cargo_release = custom_target('cargo-build',
                         output: ['gnome-podcasts'],
                         install: true,
                         install_dir: podcasts_bindir,
+                        console: true,
                         command: [cargo_script,
                                   '@CURRENT_SOURCE_DIR@',
                                   '@OUTPUT@',