Update alpine Docker tag to v3.18.2

Dockerfile

@@ -3,7 +3,7 @@ COPY . /src
 WORKDIR /src
 RUN go build -o gowon-congratulations
 
-FROM alpine:3.14.3
+FROM alpine:3.18.2
 WORKDIR /app
 COPY --from=build-env /src/gowon-congratulations /app/
 ENTRYPOINT ["./gowon-congratulations"]