Fix branch problem in build.lock file

* Also add cffi pin for py35 for charm-tools build support.
* This charm is broken at this state (as a 21.10 candidate), but will be
  fixed via a cherry pick of I4e63e64612554d74ffaca5c4e07b90f7ceb88d59
  which resolves the hacluster 'common.py' import and also restarting
  services after config-changed.

This is juju/charm-tools#604.

Change-Id: I00f4bc8251d9dc5e8f082539dfff96b972e115d2

requirements.txt

@@ -9,6 +9,7 @@
 setuptools<50.0.0  # https://github.com/pypa/setuptools/commit/04e3df22df840c6bb244e9b27bc56750c44b7c85
 
 # Build requirements
+cffi==1.14.6; python_version < '3.6'  # cffi 1.15.0 drops support for py35.
 charm-tools==2.8.3
 
 simplejson

src/build.lock

@@ -101,7 +101,7 @@
       "item": "interface:ceph-client",
       "url": "https://opendev.org/openstack/charm-interface-ceph-client.git",
       "vcs": null,
-      "branch": null,
+      "branch": "3ca251fb01a7cd51d2a0ee2b9b66647c8ffe891f",
       "commit": "3ca251fb01a7cd51d2a0ee2b9b66647c8ffe891f"
     },
     {
@@ -233,4 +233,4 @@
       "version": "21.10.1"
     }
   ]
-}
+}