Initial commit for new 1.6 release with Postgres 13 support. (#1257)

* Initial commit for new 1.6 release with Postgres 13 support.
* Updating maintainers, Go version, Codeowners.
* Use lazy upgrade image that contains pg13.
* fix typo for ownerReference
* fix clusterrole in helm chart
* reflect GCP logical backup in validation
* improve PostgresTeam docs
* change defaults for enable_pgversion_env_var and storage_resize_mode
* explain manual part of in-place upgrade
* remove gsoc docs

Co-authored-by: Felix Kunde <felix-kunde@gmx.de>

pkg/cluster/connection_pooler_test.go

@@ -778,7 +778,7 @@ func TestConnectionPoolerDeploymentSpec(t *testing.T) {
 			},
 			expected: nil,
 			cluster:  cluster,
-			check:    testDeploymentOwnwerReference,
+			check:    testDeploymentOwnerReference,
 		},
 		{
 			subTest: "selector",
@@ -931,7 +931,7 @@ func TestConnectionPoolerServiceSpec(t *testing.T) {
 				ConnectionPooler: &acidv1.ConnectionPooler{},
 			},
 			cluster: cluster,
-			check:   testServiceOwnwerReference,
+			check:   testServiceOwnerReference,
 		},
 		{
 			subTest: "selector",