`copilot-theorem`: Relax version constraint on `what4`. Refs #461.

[ivanperez-keera]

Extend range of versions of what4 supported, as prescribed in the solution proposed for #461.

[ivanperez-keera]

Change Manager: Verified that:

• Solution is implemented:

  • [X] The code proposed compiles and passes all tests. Details: Build log: https://app.travis-ci.com/github/Copilot-Language/copilot/builds/267041967

  • [X] The solution proposed produces the expected result. Details: The following Dockerfile checks Copilot can be installed with what4-1.5.1, in which case it prints the message Success:

    
    FROM ubuntu:focal

  RUN apt-get update

  RUN apt-get install --yes libz-dev RUN apt-get install --yes git

  RUN apt-get install --yes wget RUN mkdir -p $HOME/.ghcup/bin RUN wget https://downloads.haskell.org/~ghcup/0.1.19.2/x86_64-linux-ghcup-0.1.19.2 -O $HOME/.ghcup/bin/ghcup

  RUN chmod a+x $HOME/.ghcup/bin/ghcup ENV PATH=$PATH:/root/.ghcup/bin/ ENV PATH=$PATH:/root/.cabal/bin/ RUN apt-get install --yes curl RUN apt-get install --yes gcc g++ make libgmp3-dev

  SHELL ["/bin/bash", "-c"]

  RUN ghcup install ghc 9.4 RUN ghcup install cabal 3.8 RUN ghcup set ghc 9.4.7 RUN cabal update

  CMD git clone $REPO \ && cd $NAME \ && git checkout $COMMIT \ && cabal install --lib copilot**/ \ --constraint="what4==1.5.1" \ && echo Success

  Command (substitute variables based on new path after merge):

  $ docker run -e "REPO=https://github.com/ivanperez-keera/copilot" -e "NAME=copilot" -e "COMMIT=9ef909503cba54d1df741292230d716dbf30b2fb" -it copilot-verify-461

• [X] Implementation is documented. Details: No documentation needed.
• [X] Change history is clear.
• [X] Commit messages are clear.
• [X] Changelogs are updated.
• [X] Examples are updated. Details: No updates needed.
• [X] Required version bumps are evaluated. Details: Bump not needed (new versions allowed but not required).