impact add v before version number for impactometre

impactometre/back/Dockerfile

 FROM node:14-alpine as build
 
-ARG VERSION=1.2
+ARG VERSION=v1.2
 RUN apk add --no-cache unzip
 
 # Get the release

impactometre/front/Dockerfile

-ARG VERSION=1.3
+ARG VERSION=v1.3
 # Use a multi stage build : first compile and minify JS files, then serve them with a simple nginx
 FROM node:14-alpine as build