simulators/ethereum/pyspec: update execution-spec-tests (ethereum#865)

Updates execution-spec-tests version, which includes the same beacon
root contract address as the existing engine-api tests

simulators/ethereum/pyspec/Dockerfile

@@ -21,7 +21,7 @@ COPY --from=builder /source/pyspec/pyspec .
 # To run locally generated fixtures, comment the following RUN lines and
 # uncomment the ADD line.
 # Download the latest fixture release.
-RUN wget https://github.com/ethereum/execution-spec-tests/releases/download/v1.0.2/fixtures.tar.gz
+RUN wget https://github.com/ethereum/execution-spec-tests/releases/download/v1.0.3/fixtures.tar.gz
 RUN tar -xzvf fixtures.tar.gz
 RUN mv fixtures /fixtures