Update Makefile (#4011)

Update pgmonitor to 5.1.1

Author: benjaminjb

Makefile

@@ -6,7 +6,7 @@ PGO_IMAGE_URL ?= https://www.crunchydata.com/products/crunchy-postgresql-for-kub
 PGO_IMAGE_PREFIX ?= localhost
 
 PGMONITOR_DIR ?= hack/tools/pgmonitor
-PGMONITOR_VERSION ?= v5.1.1-RC1
+PGMONITOR_VERSION ?= v5.1.1
 QUERIES_CONFIG_DIR ?= hack/tools/queries
 
 EXTERNAL_SNAPSHOTTER_DIR ?= hack/tools/external-snapshotter