Resolve "srtool no more builds the WASM"

Closes #189 (closed)

docker/Dockerfile

@@ -24,6 +24,8 @@ COPY . .
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y clang cmake protobuf-compiler
 
+RUN rustup component add rust-src
+
 # build duniter
 ARG debug=0
 RUN if [ "$debug" = 0 ]; then \