Remove dependency on swh-scheduler without the 'server' extra

requirements-swh.txt

+# These dependencies will be installed by deposit clients.
+# Server dependencies go to requirements-swh-server.txt instead.
+
 swh.core[http] >= 0.4
 swh.model >= 4.4.0
-swh.scheduler

requirements.txt

+# These dependencies will be installed by deposit clients.
+# Server dependencies go to requirements-server.txt instead.
+
 click
 iso8601
 requests
-sentry-sdk
\ No newline at end of file
+sentry-sdk