update Dockerfile to specific version and use of nonroot user (#266)

* using alpine specific version instead of latest
* running container with nonroot user

Dockerfile

@@ -20,8 +20,12 @@ COPY src/ .
 RUN CGO_ENABLED=0 go build -ldflags="-w -s -X 'main.apiVersion=${apiVersion}'" -o app ./...
 
 
-# get latest alpine container
-FROM alpine:latest
+# get alpine container
+FROM alpine:alpine:3.19.1
+
+# create nonroot user
+RUN addgroup -S nonroot \
+  && adduser -S nonroot -G nonroot
 
 # add ca-certificates
 RUN apk --no-cache add ca-certificates tzdata
@@ -32,6 +36,9 @@ WORKDIR /root/
 # copy binary from first container
 COPY --from=0 /go/src/app .
 
+# set user
+USER nonroot
+
 # expose port 8080
 EXPOSE 8080