package/protobuf: update github url

protobuf moved from the google org to protocolbuffers in 2018.
There is a redirect but we should use the official url.

Signed-off-by: Michael Nosthoff <buildroot@heine.tech>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/protobuf/protobuf.mk

@@ -9,7 +9,7 @@
 # as they share the same version/site variables.
 PROTOBUF_VERSION = 3.17.3
 PROTOBUF_SOURCE = protobuf-cpp-$(PROTOBUF_VERSION).tar.gz
-PROTOBUF_SITE = https://github.com/google/protobuf/releases/download/v$(PROTOBUF_VERSION)
+PROTOBUF_SITE = https://github.com/protocolbuffers/protobuf/releases/download/v$(PROTOBUF_VERSION)
 PROTOBUF_LICENSE = BSD-3-Clause
 PROTOBUF_LICENSE_FILES = LICENSE
 PROTOBUF_CPE_ID_VENDOR = google