Add sherlock to requirements

sherlock is a simple project to cover kubernetes lock and other lock
drivers.

- Is the library actively maintained?
YES. It still been actively maintained and with around 235 contributors
in total.

- Is the library good code?
Yes

- Is the library python 3 compatible?
Yes

- Is the library license compatible?
Yes, MIT.

- Is the library already packaged in the distros we target
  (Ubuntu latest / Fedora latest)?
Yes

- Is the function of this library already covered by other libraries
  in global-requirements.txt?
No

- Is the library required for OpenStack project or related dev
  or infrastructure setup? (Answer to this should be Yes, of course) Which?
Not yet. It wil be required by tooz once we introduce kubernetes lock in
tooz.

- If the library release is managed by the Openstack release process
  does it use the cycle-with-intermediary release type?
No

Needed-By: https://review.opendev.org/c/openstack/tooz/+/897561

Change-Id: I8f77de6714dfe221e35c62f9f1e74da225d5a7fd

global-requirements.txt

@@ -387,6 +387,7 @@ oslo.versionedobjects  # Apache-2.0
 oslo.vmware  # Apache-2.0
 osprofiler  # Apache-2.0
 pbr!=2.1.0  # Apache-2.0
+sherlock  # MIT
 stevedore!=3.0.0  # Apache-2.0
 tap-as-a-service  # Apache-2.0
 taskflow  # Apache-2.0

upper-constraints.txt

@@ -366,6 +366,7 @@ opentracing===2.4.0
 XStatic-Rickshaw===1.5.1.0
 iso8601===2.1.0
 tooz===6.3.0
+sherlock===0.4.1
 idna===3.10
 yamlloader===1.4.1
 protobuf===4.25.5