Merge branch 'develop-remove-uTypeType'. Close #615.

**Description**

The record field `uTypeType`, part of `Copilot.Core.Type.UType`, is never
really used within the module or in any other part of Copilot or, as far as we
know, by any user of Copilot.

The record field was deprecated in Copilot 4.1 and no messages have been
received requesting that it be kept in this library.

As per our internal policy of waiting 3 versions from deprecation until a
public interface declaration can be removed, this definition can now be
removed.

**Type**

- Management: remove deprecated code.

**Additional context**

- Issue #484 , addressed in Copilot 4.1, deprecated the definition.

**Requester**

- Ivan Perez

**Method to check presence of bug**

Not applicable (not a bug).

**Expected result**

Running the check below prints a message indicating that the field imported
does not exist:

```
$ runhaskell <<< 'import Copilot.Core(uTypeType); main = return ()'
```

The following Dockerfile tries to import the deprecated record field,
succeeding only when the import fails, after which prints the message
"Success":

```Dockerfile
FROM ubuntu:focal

ENV DEBIAN_FRONTEND=noninteractive
RUN apt-get update

RUN apt-get install --yes \
      libz-dev \
      git \
      curl \
      gcc \
      g++ \
      make \
      libgmp3-dev  \
      pkg-config \
      z3

RUN mkdir -p $HOME/.ghcup/bin
RUN curl https://downloads.haskell.org/~ghcup/0.1.40.0/x86_64-linux-ghcup-0.1.40.0 -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/

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

RUN ghcup install ghc 9.10.1
RUN ghcup install cabal 3.2
RUN ghcup set ghc 9.10.1
RUN cabal update

SHELL ["/bin/bash", "-c"]
CMD git clone $REPO && cd $NAME && git checkout $COMMIT && cd .. \
  && cabal v1-sandbox init \
  && cabal v1-install alex happy --constraint='happy <= 2' \
  && cabal v1-install $NAME/copilot**/ \
  && ! cabal v1-exec -- runhaskell <<< 'import Copilot.Core(uTypeType); main = return ()' \
  && echo "Success"
```

Command (substitute variables based on new path after merge):
```
$ docker run -e "REPO=https://github.com/Copilot-Language/copilot" -e "NAME=copilot" -e "COMMIT=<HASH>" -it copilot-verify-615
```

**Solution implemented**

Remove the deprecated definition `copilot-core:Copilot.Core.Type.uTypeType`.

**Further notes**

None.

Author: ivanperez-keera

copilot-core/CHANGELOG

@@ -1,3 +1,6 @@
+2025-04-21
+        * Remove deprecated Copilot.Core.Type.uTypeType. (#615)
+
 2025-03-07
         * Version bump (4.3). (#604)
         * Fix typo in documentation. (#587)

copilot-core/src/Copilot/Core/Type.hs

@@ -289,8 +289,7 @@ instance (Typeable t, Typed t, KnownNat n) => Typed (Array n t) where
   simpleType (Array t) = SArray t
 
 -- | A untyped type (no phantom type).
-data UType = forall a . Typeable a => UType { uTypeType :: Type a }
-{-# DEPRECATED uTypeType "This field is deprecated in Copilot 4.1. Use pattern matching instead." #-}
+data UType = forall a . Typeable a => UType (Type a)
 
 instance Eq UType where
   UType ty1 == UType ty2 = typeRep ty1 == typeRep ty2