MM-52679: Bump up minimum postgres version to 11 (#23315)

https://mattermost.atlassian.net/browse/MM-52679
```release-note
NONE
```

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/store/sqlstore/store.go

@@ -56,7 +56,7 @@ const (
 	// After 10, it's major and minor only.
 	// 10.1 would be 100001.
 	// 9.6.3 would be 90603.
-	minimumRequiredPostgresVersion = 100000
+	minimumRequiredPostgresVersion = 110000
 	// major*1000 + minor*100 + patch
 	minimumRequiredMySQLVersion = 5712
 

server/channels/store/sqlstore/store_test.go

@@ -436,6 +436,12 @@ func TestEnsureMinimumDBVersion(t *testing.T) {
 		{
 			driver: model.DatabaseDriverPostgres,
 			ver:    "100001",
+			ok:     false,
+			err:    "",
+		},
+		{
+			driver: model.DatabaseDriverPostgres,
+			ver:    "110001",
 			ok:     true,
 			err:    "",
 		},