Geo: wal_keep_size being incorrectly set in Postgres 13

When setting up Geo with Postgres 13, adding the config to point the secondary patroni cluster at the primary, the Postgres runtime config file (/var/opt/gitlab/geo-postgresql/data/runtime.conf) is being broken, wal_keep_size is not being given a value and as such the geo-postgresql service is not able to start.

wal_keep_size =

2021-09-10_15:12:17.65846 2021-09-10 15:12:17.658 GMT [6442] LOG:  syntax error in file "/var/opt/gitlab/geo-postgresql/data/runtime.conf" line 30, near end
 of line
2021-09-10_15:12:17.65873 2021-09-10 15:12:17.658 GMT [6442] FATAL:  configuration file "/var/opt/gitlab/geo-postgresql/data/postgresql.conf" contains error
s

/cc @geo-team