cmd/worker: update Go version to the one before the last one

Change-Id: I82f4180752525c6c833e40b75240a9e09cc0bf45
Reviewed-on: https://go-review.googlesource.com/c/pkgsite-metrics/+/538777
TryBot-Result: Gopher Robot <gobot@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Run-TryBot: Zvonimir Pavlinovic <zpavlinovic@google.com>
Reviewed-by: Maceo Thompson <maceothompson@google.com>
diff --git a/cmd/worker/Dockerfile b/cmd/worker/Dockerfile
index ae91097..a040e9c 100644
--- a/cmd/worker/Dockerfile
+++ b/cmd/worker/Dockerfile
@@ -13,7 +13,7 @@
 # installed here will be shadowed.
 
 
-FROM golang:1.20.7
+FROM golang:1.21.2
 
 LABEL maintainer="Go Ecosystem Team <go-ecosystem-team@google.com>"