Bump golang from 1.20-alpine to 1.21-alpine

Bumps golang from 1.20-alpine to 1.21-alpine.

---
updated-dependencies:
- dependency-name: golang
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Dockerfile

@@ -1,5 +1,5 @@
 # Build Stage: Build bot using the golang image
-FROM golang:1.20-alpine AS builder
+FROM golang:1.21-alpine AS builder
 RUN apk add --no-cache curl wget gnupg git upx
 WORKDIR /app
 COPY . .