cherry-pick: all: upd dnsproxy

Updates #3977.

Squashed commit of the following:

commit 3aaaacac102cdea04ae46b36d2dd3a3be7d50147
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Dec 23 16:15:11 2021 +0300

    all: upd dnsproxy

bamboo-specs/release.yaml

@@ -7,7 +7,7 @@
 # Make sure to sync any changes with the branch overrides below.
 'variables':
   'channel': 'edge'
-  'dockerGo': 'adguard/golang-ubuntu:3.8'
+  'dockerGo': 'adguard/golang-ubuntu:4.0'
 
 'stages':
 - 'Make release':
@@ -266,7 +266,7 @@
     # need to build a few of these.
     'variables':
       'channel': 'beta'
-      'dockerGo': 'adguard/golang-ubuntu:3.8'
+      'dockerGo': 'adguard/golang-ubuntu:4.0'
 # release-vX.Y.Z branches are the branches from which the actual final release
 # is built.
 - '^release-v[0-9]+\.[0-9]+\.[0-9]+':
@@ -276,4 +276,4 @@
     # are the ones that actually get released.
     'variables':
       'channel': 'release'
-      'dockerGo': 'adguard/golang-ubuntu:3.8'
+      'dockerGo': 'adguard/golang-ubuntu:4.0'

bamboo-specs/test.yaml

@@ -5,7 +5,7 @@
   'key': 'AHBRTSPECS'
   'name': 'AdGuard Home - Build and run tests'
 'variables':
-  'dockerGo': 'adguard/golang-ubuntu:3.8'
+  'dockerGo': 'adguard/golang-ubuntu:4.0'
 
 'stages':
 - 'Tests':