[#2534] added Instagram OAuth2 provider

Co-authored-by: Pedro Costa <550684+pnmcosta@users.noreply.github.com>

tools/auth/auth_test.go

@@ -180,4 +180,13 @@ func TestNewProviderByName(t *testing.T) {
 	if _, ok := p.(*auth.Apple); !ok {
 		t.Error("Expected to be instance of *auth.Apple")
 	}
+
+	// instagram
+	p, err = auth.NewProviderByName(auth.NameInstagram)
+	if err != nil {
+		t.Errorf("Expected nil, got error %v", err)
+	}
+	if _, ok := p.(*auth.Instagram); !ok {
+		t.Error("Expected to be instance of *auth.Instagram")
+	}
 }