MM-60387: Bump Go version to 1.22 (#28118)

https://mattermost.atlassian.net/browse/MM-60387
```release-note
updated Go version to 1.22
```
---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/.go-version

@@ -1 +1 @@
-1.21.8
+1.22.6

server/build/Dockerfile.buildenv

@@ -1,4 +1,4 @@
-FROM golang:1.21.8-bullseye@sha256:81d98548f08e22a59c5c0be814acc0997f3dfd3313487adcf4e1d3d962af3a43
+FROM golang:1.22.6-bullseye@sha256:0838740c99e64dde1916553b004bdb1bc321823be83bde3d2a1563882eaab7e6
 
 RUN apt-get update && apt-get install -y make git apt-transport-https ca-certificates curl software-properties-common build-essential zip xmlsec1 jq pgloader
 

server/go.mod

@@ -1,8 +1,8 @@
 module github.com/mattermost/mattermost/server/v8
 
-go 1.21.0
+go 1.22.0
 
-toolchain go1.21.8
+toolchain go1.22.6
 
 require (
 	code.sajari.com/docconv/v2 v2.0.0-pre.4

server/public/go.mod

@@ -1,8 +1,8 @@
 module github.com/mattermost/mattermost/server/public
 
-go 1.21
+go 1.22
 
-toolchain go1.21.8
+toolchain go1.22.6
 
 require (
 	github.com/blang/semver/v4 v4.0.0