using inbucket docker image tag release-1.2.0 instead of latest (#8406)

Makefile

@@ -118,7 +118,7 @@ start-docker: ## Starts the docker containers for local development.
 
 	@if [ $(shell docker ps -a | grep -ci mattermost-inbucket) -eq 0 ]; then \
 		echo starting mattermost-inbucket; \
-		docker run --name mattermost-inbucket -p 9000:10080 -p 2500:10025 -d jhillyerd/inbucket:latest > /dev/null; \
+		docker run --name mattermost-inbucket -p 9000:10080 -p 2500:10025 -d jhillyerd/inbucket:release-1.2.0 > /dev/null; \
 	elif [ $(shell docker ps | grep -ci mattermost-inbucket) -eq 0 ]; then \
 		echo restarting mattermost-inbucket; \
 		docker start mattermost-inbucket > /dev/null; \

build/Jenkinsfile

@@ -31,7 +31,7 @@ podTemplate(label: 'jenkins-slave',
         ),
         containerTemplate(
             name: 'mattermost-inbucket',
-            image: 'jhillyerd/inbucket:latest',
+            image: 'jhillyerd/inbucket:release-1.2.0',
             resourceRequestCpu: '250m',
             resourceLimitCpu: '250m',
             resourceRequestMemory: '256Mi',