main/postmarketos-test: let tests add additional files to the initramfs

This will be used in follow-up commits to bring in more tests from
other packages in pmaports

Signed-off-by: Pablo Correa Gómez <pabloyoyoista@postmarketos.org>
Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/7881>

main/postmarketos-test/APKBUILD

@@ -1,6 +1,6 @@
 maintainer="Casey Connolly <kcxt@postmarketos.org>"
 pkgname=postmarketos-test
-pkgver=1.2.0
+pkgver=1.3.0
 pkgrel=0
 pkgdesc="Common test utilities for postmarketOS"
 url="https://postmarketos.org"
@@ -33,11 +33,16 @@ _test() {
 	_testname=${subpkgname#postmarketos-test-}
 
 	_script="$srcdir"/*"$_testname"-test.sh
+	_files="$srcdir"/*"$_testname"-files.files
 
 	if [ -f $_script ]; then
 		install -Dm755 $_script \
 			-t "$subpkgdir"/usr/libexec/pmos-tests-initramfs/
 	fi
+	if [ -f $_files ]; then
+		install -Dm644 $_files \
+			-t "$subpkgdir"/usr/share/mkinitfs/files/
+	fi
 }
 
 # Installs a "test" which just runs a shell on the console for debugging