build(deps): bump golang in /examples/xds-sotw-config-server (#770)

Bumps golang from `d56c3e0` to `73f06be`.

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

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

examples/xds-sotw-config-server/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.23.3@sha256:d56c3e08fe5b27729ee3834854ae8f7015af48fd651cd25d1e3bcf3c19830174 AS build
+FROM golang:1.23.3@sha256:73f06be4578c9987ce560087e2e2ea6485fb605e3910542cadd8fa09fc5f3e31 AS build
 WORKDIR /xds-server
 
 COPY . .