Update label creation (#563)

Add the description to the label.

Author: Mariatta

bedevere/backport.py

@@ -130,5 +130,6 @@ async def maintenance_branch_created(event, gh, *args, **kwargs):
     if MAINTENANCE_BRANCH_RE.match(branch_name):
         await gh.post(
             "/repos/python/cpython/labels",
-            data={"name": f"needs backport to {branch_name}", "color": "c2e0c6"},
+            data={"name": f"needs backport to {branch_name}", "color": "c2e0c6",
+                  "description": "bug and security fixes"},
         )

tests/test_backport.py

@@ -452,7 +452,8 @@ async def test_maintenance_branch_created(ref):
     await backport.router.dispatch(event, gh)
     label_creation_post = gh.post_[0]
     assert label_creation_post[0] == "https://api.github.com/repos/python/cpython/labels"
-    assert label_creation_post[1] == {'name': f"needs backport to {ref}", 'color': 'c2e0c6'}
+    assert label_creation_post[1] == {'name': f"needs backport to {ref}", 'color': 'c2e0c6',
+                                      'description': 'bug and security fixes'}
 
 
 @pytest.mark.parametrize('ref', ['backport-3.9', 'test', 'Mariatta-patch-1'])