Add test data for modulemd-packager-v3 src file [RHELDST-3923] (#45)

Added module source file with packager-v3 format for tests.
Updated test for use this new test data.

tests/data/module_source/packager-modulemd.src.txt

@@ -0,0 +1,22 @@
+document: modulemd-packager
+version: 3
+data:
+    summary: A test module in all its beautiful beauty.
+    description: >-
+        A module for the demonstration of the metadata format. Also,
+        the obligatory lorem ipsum dolor sit amet goes right here.
+    configurations:
+        - context: testctx1
+          platform: el8.1.0.z
+          buildrequires:
+              testmodule: [test-reuse-tagged-module]
+          requires:
+              platform: el8.1.0.z
+          buildopts:
+              arches: [x86_64]
+    components:
+        rpms:
+            attr:
+                rationale: A build dependency of acl
+                ref: rhel-8.1.0
+                arches: [x86_64]

tests/test_rpms.py

@@ -1025,13 +1025,16 @@ def test_unsupported_source_startup_error():
     mock_options = MagicMock(koji=True, source="build_nvr.src.foo")
     assert_that(calling(BaseProcessor).with_args(mock_options), raises(StartupError))
 
-
+@pytest.mark.parametrize('source_module', [
+    'fake-nvr:modulemd.src.txt',
+    'fake-nvr:packager-modulemd.src.txt',
+])
 def test_stage_module_src(config_file, pushdir, lookasidedir, capsys, default_config,
-                          mock_koji_session, mock_koji_pathinfo):
+                          mock_koji_session, mock_koji_pathinfo, source_module):
     """Verify that alt-src command completes without any errors and generates
     a commit for the given module source."""
     branch = 'c7'
-    modulemd = 'fake-nvr:modulemd.src.txt'
+    modulemd = source_module
 
     options = ['-v',
                '-c', config_file,