Bump golang image (#16314)

* Fix images

* Add golangci-lint also

* Bump golang image

* Replace tag

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

.gitlab-ci.yml

@@ -33,7 +33,7 @@ empty:
 #    - if: '$ONLY_BUILD != "yes"'
 #
 #layers:
-#  image: $CI_REGISTRY/mattermost/ci/images/mattermost-build-server:20201023_golang-1.14.6
+#  image: $CI_REGISTRY/mattermost/ci/images/mattermost-build-server:20201119_golang-1.15.5
 #  stage: .pre
 #  script:
 #    - make store-layers
@@ -81,7 +81,7 @@ empty:
 #        --env MM_SQLSETTINGS_DRIVERNAME=postgres \
 #        -v $CI_PROJECT_DIR:/mattermost-server \
 #        -w /mattermost-server \
-#        mattermost/mattermost-build-server:20201023_golang-1.14.6 \
+#        mattermost/mattermost-build-server:20201119_golang-1.15.5 \
 #        bash -c "ulimit -n 8096; make ARGS='version' run-cli && make MM_SQLSETTINGS_DATASOURCE='postgres://mmuser:mostest@postgres:5432/latest?sslmode=disable&connect_timeout=10' ARGS='version' run-cli"
 #    - docker logs -f server-postgres
 #    - echo "Generating dump"
@@ -110,7 +110,7 @@ empty:
 #        --env MM_SQLSETTINGS_DRIVERNAME=mysql \
 #        -v $CI_PROJECT_DIR:/mattermost-server \
 #        -w /mattermost-server \
-#        mattermost/mattermost-build-server:20201023_golang-1.14.6 \
+#        mattermost/mattermost-build-server:20201119_golang-1.15.5 \
 #        bash -c "ulimit -n 8096; make ARGS='version' run-cli && make MM_SQLSETTINGS_DATASOURCE='mmuser:mostest@tcp(mysql:3306)/latest?charset=utf8mb4,utf8&readTimeout=30s&writeTimeout=30s' ARGS='version' run-cli"
 #    - docker logs -f server-mysql
 #    - echo "Ignoring known MySQL mismatch 'ChannelMembers.SchemeGuest'"