reformat code (#2019)

* reformat code

This is mostly an automated change with `make lint`.
I had to manually please golangci-lint in routes_test because of a short
variable name.

* fix start -> strategy which was wrongly corrected by linter

hscontrol/oidc.go

@@ -57,7 +57,6 @@ func (h *Headscale) initOIDC() error {
 	// grab oidc config if it hasn't been already
 	if h.oauth2Config == nil {
 		h.oidcProvider, err = oidc.NewProvider(context.Background(), h.cfg.OIDC.Issuer)
-
 		if err != nil {
 			return fmt.Errorf("creating OIDC provider from issuer config: %w", err)
 		}