Move operator to go 1.14 (#882)

* update go modules march 2020
* update to GO 1.14
* reflect k8s client API changes

go.mod

@@ -1,26 +1,19 @@
 module github.com/zalando/postgres-operator
 
-go 1.12
+go 1.14
 
 require (
-	github.com/aws/aws-sdk-go v1.25.44
-	github.com/emicklei/go-restful v2.9.6+incompatible // indirect
-	github.com/evanphx/json-patch v4.5.0+incompatible // indirect
-	github.com/googleapis/gnostic v0.3.0 // indirect
-	github.com/imdario/mergo v0.3.8 // indirect
-	github.com/lib/pq v1.2.0
+	github.com/aws/aws-sdk-go v1.29.33
+	github.com/lib/pq v1.3.0
 	github.com/motomux/pretty v0.0.0-20161209205251-b2aad2c9a95d
-	github.com/sirupsen/logrus v1.4.2
+	github.com/r3labs/diff v0.0.0-20191120142937-b4ed99a31f5a
+	github.com/sirupsen/logrus v1.5.0
 	github.com/stretchr/testify v1.4.0
-	golang.org/x/crypto v0.0.0-20191206172530-e9b2fee46413 // indirect
-	golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553 // indirect
-	golang.org/x/sys v0.0.0-20191210023423-ac6580df4449 // indirect
-	golang.org/x/tools v0.0.0-20191209225234-22774f7dae43 // indirect
-	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
-	gopkg.in/yaml.v2 v2.2.4
-	k8s.io/api v0.0.0-20191121015604-11707872ac1c
-	k8s.io/apiextensions-apiserver v0.0.0-20191204090421-cd61debedab5
-	k8s.io/apimachinery v0.0.0-20191203211716-adc6f4cd9e7d
-	k8s.io/client-go v0.0.0-20191204082520-bc9b51d240b2
-	k8s.io/code-generator v0.0.0-20191121015212-c4c8f8345c7e
+	golang.org/x/tools v0.0.0-20200326210457-5d86d385bf88 // indirect
+	gopkg.in/yaml.v2 v2.2.8
+	k8s.io/api v0.18.0
+	k8s.io/apiextensions-apiserver v0.18.0
+	k8s.io/apimachinery v0.18.0
+	k8s.io/client-go v0.18.0
+	k8s.io/code-generator v0.18.0
 )