Bump redis-rails to 5.0.2 to get redis-store security updates

Other change highlights:

redis-actionpack 5.0.1 -> 5.0.2:

• Loosen dependencies to work with new minor redis-store versions

redis-activesupport 5.0.1 -> 5.0.4:

5.0.4

• Fix Redis connection-related exceptions with read_multi and fetch_multi: https://github.com/redis-store/redis-activesupport/pull/93

5.0.3:

• Fix :raw option for read_multi
• Revert "Use SCAN for delete_matched if client and server supports it"
• Support regular expressions in delete_matched
• Extract options from names before checking its size

5.0.2:

• Add support for race_condition_ttl on fetch: https://github.com/redis-store/redis-activesupport/pull/71

redis-rack 1.6.0 -> 2.0.3:

• Add support for ConnectionPool: https://github.com/redis-store/redis-rack/commit/68163017b65da0acd37d7ce787934f55357cf9ea#diff-c50b22f679eb8e97b8f1dcda1da50f4b
• Create a :use_global_lock option that avoids the global lock: https://github.com/redis-store/redis-rack/commit/1918679a3cadb1ccb88da1dfdcba3cc0cc3eac70#diff-c50b22f679eb8e97b8f1dcda1da50f4b

Closes #40889