Update golang toolchain to 1.23.9 (#31062)

* Update golang toolchain

* remove comment

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

server/build/Dockerfile.buildenv

@@ -1,4 +1,4 @@
-FROM golang:1.23.7-bullseye@sha256:8731dcb40a7b879ccb493fa4fa38e83d9f33ca24ab60bec02e98d5af7e962cac
+FROM golang:1.23.9-bullseye@sha256:f2ea45502b0565bd554ed2d4954ef1eb434df07ff4cdb867fabb4d2a6b1c0668
 
 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