build(deps): Bump golang in /docs/best-practice/forwarding-logs-via-http (fluent#831)

Bumps golang from 1.20.4 to 1.20.6.

---
updated-dependencies:
- dependency-name: golang
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

docs/best-practice/forwarding-logs-via-http/Dockerfile

@@ -1,5 +1,5 @@
 # Build the manager binary
-FROM golang:1.20.4 as builder
+FROM golang:1.20.6 as builder
 
 WORKDIR /
 COPY main.go /go/src/main.go