sources: relax "mirror" regexp to follow upstream repo ID

This commit relaxes the "mirror" schema regex from only allow
hashes to the repo ID regex as described in
https://dnf.readthedocs.io/en/latest/conf_ref.html#description

This is needed because in e.g. bootc-image-builder we use
"SetRootDir()" to get the repository information from an existing
bootc image and there the repo_id (that is then used as the mirror_id)
is written in a human friendly way instead of hex.

Thanks to Tomáš Hozza for the suggestions and background info, see
https://github.com/osbuild/osbuild/pull/1974#issuecomment-2579325272

sources/org.osbuild.librepo

@@ -22,6 +22,9 @@ from osbuild.util.rhsm import Subscriptions
 
 # NOTE: The top level schema properties are limited to items and options by the
 # v2 schema definition
+#
+# "mirror" pattern follows dnf repo_id as described in:
+# https://dnf.readthedocs.io/en/latest/conf_ref.html#description
 SCHEMA_2 = """
 "properties": {
   "items": {
@@ -57,7 +60,7 @@ SCHEMA_2 = """
         "type": "object",
         "additionalProperties": false,
         "patternProperties": {
-          "^[0-9a-f]+$": {
+          "^[0-9a-zA-Z-._:]+$": {
             "required": [
               "url",
               "type"

sources/test/test_librepo.py

@@ -140,9 +140,9 @@ def test_librepo_secrets_mtls(mocked_download_pkgs, sources_service, monkeypatch
 @pytest.mark.parametrize("test_mirrors,expected_err", [
     # bad
     (
-        # only hashes supported for mirror_ids
-        {"bad_mirror_id": {"url": "http://example.com", "type": "mirrorlist"}},
-        "'bad_mirror_id' does not match any of the regexes: '^[0-9a-f]+$'",
+        # no spaces in mirror_id
+        {"bad mirror": {"url": "http://example.com", "type": "mirrorlist"}},
+        "'bad mirror' does not match any of the regexes: ",
     ),
     (
         {"0123456789abcdef": {"type": "mirrorlist"}},
@@ -168,7 +168,10 @@ def test_librepo_secrets_mtls(mocked_download_pkgs, sources_service, monkeypatch
     ),
     (
         {"0123": {"url": "http://example.com", "type": "baseurl"}}, "",
-    )
+    ),
+    (
+        {"Com_plex:id.": {"url": "http://x.com", "type": "baseurl"}}, "",
+    ),
 ])
 def test_schema_validation(sources_schema, test_mirrors, expected_err):
     test_input = {