Upgrade to go 1.16, upgrade dependencies and stop using deprecated method

https://pkg.go.dev/k8s.io/client-go/informers#NewFilteredSharedInformerFactory

I am a go noob, so I am not sure if I updated the dependencies in a correct way, the code builds & runs (tested it in an out-of-cluster mode) so I think it is ok, happy to tweak if further if needed.
I used `go get -u ./...` based on https://github.com/golang/go/wiki/Modules#how-to-upgrade-and-downgrade-dependencies

Author: asherf

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.13 as build
+FROM golang:1.16 as build
 WORKDIR /src
 
 COPY . .

go.mod

@@ -1,35 +1,42 @@
 module github.com/grafana/kubernetes-diff-logger
 
-go 1.13
+go 1.16
 
 require (
-	github.com/apex/log v1.1.2
-	github.com/go-test/deep v1.0.5
-	github.com/gogo/protobuf v1.3.1 // indirect
+	github.com/apex/log v1.9.0
+	github.com/dgrijalva/jwt-go v0.0.0-20160705203006-01aeca54ebda // indirect
+	github.com/docker/spdystream v0.0.0-20160310174837-449fdfce4d96 // indirect
+	github.com/ghodss/yaml v0.0.0-20150909031657-73d445a93680 // indirect
+	github.com/go-test/deep v1.0.7
 	github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e // indirect
-	github.com/golang/protobuf v1.3.4 // indirect
-	github.com/google/go-cmp v0.4.0 // indirect
-	github.com/google/gofuzz v1.1.0 // indirect
-	github.com/googleapis/gnostic v0.4.0 // indirect
+	github.com/google/go-cmp v0.5.6 // indirect
+	github.com/google/gofuzz v1.2.0 // indirect
+	github.com/googleapis/gnostic v0.5.5 // indirect
+	github.com/gophercloud/gophercloud v0.0.0-20190126172459-c818fa66e4c8 // indirect
 	github.com/hashicorp/golang-lru v0.5.4 // indirect
-	github.com/imdario/mergo v0.3.8 // indirect
-	github.com/json-iterator/go v1.1.9 // indirect
+	github.com/imdario/mergo v0.3.12 // indirect
+	github.com/json-iterator/go v1.1.11 // indirect
 	github.com/kr/text v0.2.0 // indirect
 	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
 	github.com/pkg/errors v0.9.1
 	github.com/ryanuber/go-glob v1.0.0
-	github.com/stretchr/testify v1.5.1 // indirect
-	golang.org/x/crypto v0.0.0-20200311171314-f7b00557c8c4 // indirect
-	golang.org/x/net v0.0.0-20200301022130-244492dfa37a // indirect
-	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d // indirect
-	golang.org/x/sys v0.0.0-20200302150141-5c8b2ff67527 // indirect
-	golang.org/x/time v0.0.0-20191024005414-555d28b269f0 // indirect
-	google.golang.org/appengine v1.6.5 // indirect
+	golang.org/x/crypto v0.0.0-20210616213533-5ff15b29337e // indirect
+	golang.org/x/net v0.0.0-20210614182718-04defd469f4e // indirect
+	golang.org/x/oauth2 v0.0.0-20210615190721-d04028783cf1 // indirect
+	golang.org/x/sys v0.0.0-20210616094352-59db8d763f22 // indirect
+	golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b // indirect
+	golang.org/x/time v0.0.0-20210611083556-38a9dc6acbc6 // indirect
+	google.golang.org/appengine v1.6.7 // indirect
 	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
-	gopkg.in/yaml.v2 v2.2.8
-	k8s.io/api v0.17.3
-	k8s.io/apimachinery v0.17.3
-	k8s.io/client-go v0.0.0-20190620085101-78d2af792bab
-	k8s.io/utils v0.0.0-20200229041039-0a110f9eb7ab // indirect
+	gopkg.in/yaml.v2 v2.4.0
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+	k8s.io/api v0.21.2
+	k8s.io/apimachinery v0.21.2
+	k8s.io/client-go v0.21.2
+	k8s.io/klog v1.0.0 // indirect
+	k8s.io/klog/v2 v2.9.0 // indirect
+	k8s.io/utils v0.0.0-20210527160623-6fdb442a123b // indirect
+	sigs.k8s.io/structured-merge-diff v0.0.0-20190525122527-15d366b2352e // indirect
+	sigs.k8s.io/structured-merge-diff/v4 v4.1.1 // indirect
 	sigs.k8s.io/yaml v1.2.0 // indirect
 )