Fix test runner in Dockerfile

Dockerfile

@@ -1,7 +1,7 @@
 # syntax=docker/dockerfile:1
 
 FROM alpine:latest as pythonbuilder
-RUN apk add gcc python3 python3-dev musl-dev linux-headers
+RUN apk add gcc python3 python3-dev musl-dev linux-headers libffi libffi-dev
 RUN python -m venv /opt/venv
 # Make sure we use the virtualenv:
 ENV PATH="/opt/venv/bin:$PATH"
@@ -17,7 +17,8 @@ RUN cd miniscript-cli && cargo install --path .
 FROM alpine:latest
 
 RUN apk --no-cache add curl ruby ruby-dev python3 bash build-base gcc wget git \
-    autoconf automake libtool boost-dev libevent-dev sqlite-dev zeromq-dev linux-headers musl-dev libffi yaml-dev bitcoin python3-dev pipx \
+    autoconf automake libtool boost-dev libevent-dev sqlite-dev zeromq-dev linux-headers \
+    yaml-dev bitcoin python3-dev \
     pandoc
 
 # # Install bitcoin core from source. This allows us to experiment with various forks.
@@ -29,13 +30,17 @@ RUN apk --no-cache add curl ruby ruby-dev python3 bash build-base gcc wget git \
 #     make install
 
 WORKDIR /bitcoin-dsl
-COPY Gemfile lib spec notebooks Rakefile.rb .
+COPY Gemfile Rakefile.rb .
 
 RUN gem install bundler:2.5.5 && \
     bundle install --without=development && \
     bundle binstubs --all && \
     rm -rf /usr/local/bundle/cache
 
+COPY lib lib
+COPY spec spec
+COPY notebooks notebooks
+
 COPY --from=rustbuilder /usr/local/cargo/bin/miniscript-cli /usr/local/cargo/bin/miniscript-cli
 COPY --from=pythonbuilder /opt/venv /opt/venv