Bump alpine from 3.18.3 to 3.18.4

Bumps alpine from 3.18.3 to 3.18.4.

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

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

Dockerfile.buf

@@ -13,7 +13,7 @@ ARG TARGETARCH
 RUN CGO_ENABLED=0 GOOS=${TARGETOS} GOARCH=${TARGETARCH} \
   go build -ldflags "-s -w" -trimpath -buildvcs=false -o /go/bin/buf ./cmd/buf
 
-FROM --platform=${TARGETPLATFORM} alpine:3.18.3
+FROM --platform=${TARGETPLATFORM} alpine:3.18.4
 
 RUN apk add --update --no-cache \
     ca-certificates \