Bump go version to 1.16

Also bump dependencies, so that compilation works again.

.github/workflows/build.yaml

@@ -26,7 +26,7 @@ jobs:
     - name: Setup go
       uses: actions/setup-go@v2
       with:
-        go-version: 1.15.15
+        go-version: 1.16.8
     - name: Build binary
       run: make
     - name: Compress binary

go.mod

@@ -1,15 +1,11 @@
 module github.com/twz123/oidc-token-ferry
 
-go 1.14
+go 1.16
 
 require (
-	github.com/coreos/go-oidc v2.2.1+incompatible
-	github.com/imdario/mergo v0.3.9 // indirect
+	github.com/coreos/go-oidc/v3 v3.1.0
 	github.com/jessevdk/go-flags v1.5.0
 	github.com/pkg/errors v0.9.1
-	github.com/pquerna/cachecontrol v0.0.0-20180517163645-1555304b9b35 // indirect
-	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d
-	google.golang.org/appengine v1.6.6 // indirect
-	gopkg.in/square/go-jose.v2 v2.5.1 // indirect
-	k8s.io/client-go v0.21.0
+	golang.org/x/oauth2 v0.0.0-20210819190943-2bc19b11175f
+	k8s.io/client-go v0.22.1
 )