Migrate to charmcraft 2.x

charmcraft 2.1 build is failing because of dependency changes
so migrate to 2.x given that it builds successfully
on 2.x.

Also specifically for Antelope: fixing broken cython_sources
error when buliding PyYAML 6.0, therefore bumping to 6.0.1.

Change-Id: I27e3331ff2b6f1cdb03bfb4e11ba275558effd00

Author: Rodrigo Barbieri

osci.yaml

@@ -6,3 +6,4 @@
       needs_charm_build: true
       charm_build_name: keystone-openidc
       build_type: charmcraft
+      charmcraft_channel: 2.x/stable

requirements.txt

@@ -8,7 +8,7 @@ netaddr==0.8.0
 ops==2.2.0
 git+https://opendev.org/openstack/charm-ops-openstack@master#egg=ops_openstack
 pbr==5.11.1
-PyYAML==6.0
+PyYAML==6.0.1
 requests==2.28.2
 urllib3==1.26.15
 websocket-client==1.5.1