Bump golang in /examples/deployment/docker/db_client (#3064)

Bumps golang from 1.19-buster to 1.20-buster.

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

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

examples/deployment/docker/db_client/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.19-buster
+FROM golang:1.20-buster
 
 RUN apt-get update && \
     apt-get install -y mariadb-client