pmb.chroot.apk_static: use sha256 sig for verification

Folks using pmb v2 on Fedora and other distros that disabled sha1 in openssl will need this in order to run pmb successfully.

Backported from 7a299b3f

test/test_apk_static.py

@@ -56,7 +56,7 @@ def test_read_signature_info(args):
     # Signature file with realistic name
     path = glob.glob(pmb.config.apk_keys_path + "/*.pub")[0]
     name = os.path.basename(path)
-    path_archive = "sbin/apk.static.SIGN.RSA.sha256" + name
+    path_archive = "sbin/apk.static.SIGN.RSA.sha256." + name
     pmb.chroot.user(args, ["mv",
                            f"{tmp_path}/sbin/apk.static.SIGN.RSA.sha256.invalid.pub",
                            f"{tmp_path}/{path_archive}"])