dflash2 build.sh: strip shell quotes from versions.env values before --build-arg

docker-images/glm53-flash-dflash2/build.sh

@@ -15,6 +15,7 @@ while IFS= read -r line; do
         ''|\#*) continue ;;
     esac
     key="${line%%=*}"; val="${line#*=}"
+    val="${val%\"}"; val="${val#\"}"   # versions.env values may be shell-quoted
     [ -n "$key" ] && ARGS+=(--build-arg "${key}=${val}")
 done < versions.env