diff: remove Differ code

In favor of the new `Diff` action.

Signed-off-by: Hidde Beydals <hidde@hhh.computer>

Author: hiddeco

go.mod

@@ -15,7 +15,6 @@ replace (
 )
 
 require (
-	github.com/fluxcd/cli-utils v0.36.0-flux.1
 	github.com/fluxcd/helm-controller/api v0.36.2
 	github.com/fluxcd/pkg/apis/acl v0.1.0
 	github.com/fluxcd/pkg/apis/event v0.6.0
@@ -78,6 +77,7 @@ require (
 	github.com/evanphx/json-patch/v5 v5.7.0 // indirect
 	github.com/exponent-io/jsonpath v0.0.0-20210407135951-1de76d718b3f // indirect
 	github.com/fatih/color v1.13.0 // indirect
+	github.com/fluxcd/cli-utils v0.36.0-flux.1 // indirect
 	github.com/fsnotify/fsnotify v1.6.0 // indirect
 	github.com/go-errors/errors v1.4.2 // indirect
 	github.com/go-gorp/gorp/v3 v3.1.0 // indirect