CI: tweak again

.github/workflows/ci.yml

@@ -33,7 +33,6 @@ jobs:
     - name: Setup toolchain
       run: |
         curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | BOOTSTRAP_HASKELL_NONINTERACTIVE=1 BOOTSTRAP_HASKELL_INSTALL_NO_STACK=1 BOOTSTRAP_HASKELL_GHC_VERSION=${{ matrix.ghc }} BOOTSTRAP_HASKELL_ADJUST_BASHRC=yes sh
-        . ~/.ghcup/env
     - uses: actions/cache@v4
       name: Cache cabal stuff
       with:
@@ -43,6 +42,7 @@ jobs:
         key: ${{ runner.os }}-${{ matrix.ghc }}
     - name: Build
       run: |
+        . ~/.ghcup/env
         ghc --version
         cabal --version
         cabal update