Bump golang in /binary_transparency/firmware/cmd/ftmapserver (#867)

Bumps golang from 1.20.3-buster to 1.20.5-buster.

---
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>

binary_transparency/firmware/cmd/ftmapserver/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.20.3-buster@sha256:73c225bc5e2353f20dbe0466819b70a51a114a93bfe4af035a3bb9e1ecdd4107 AS builder
+FROM golang:1.20.5-buster@sha256:eb3f9ac805435c1b2c965d63ce460988e1000058e1f67881324746362baf9572 AS builder
 LABEL stage=builder
 
 ARG GOFLAGS=""
@@ -20,7 +20,7 @@ COPY . .
 RUN go build ./binary_transparency/firmware/cmd/ftmapserver
 
 # Build release image
-FROM golang:1.20.3-buster@sha256:73c225bc5e2353f20dbe0466819b70a51a114a93bfe4af035a3bb9e1ecdd4107
+FROM golang:1.20.5-buster@sha256:eb3f9ac805435c1b2c965d63ce460988e1000058e1f67881324746362baf9572
 
 COPY --from=builder /build/ftmapserver /bin/ftmapserver
 ENTRYPOINT ["/bin/ftmapserver"]