CI: caching: fx cabal.project copying

In the
https://github.com/haskell/haskell-language-server/runs/4596861600?check_suite_focus=true
of
#2503

Noted that:

I rm cabal.project. The sources of cabal-ghc921.project contain:
index-state: 2021-12-18T00:00:07Z
cp cabal-ghc921.project cabal.project
Then from cabal.project CI retrieves finderprint 2021-11-29T08:11:08Z.
Seems like GitHub uses alias cp=cp -i - preventing UNIX-like default copying over behaviour.
& rm cabal.project does not remove the file.
cabal.project seems to be protected from deletion.

Author: Anton-Latukha

.github/workflows/caching.yml

@@ -100,7 +100,8 @@ jobs:
       - if: matrix.ghc == '9.0.1'
         name: (GHC 9.0.1) Use modified `cabal.project`
         run: |
-          cp cabal-ghc901.project cabal.project
+          # This seems insane, but it is needed.
+          rm -f -v cabal.project && cp -v cabal-ghc901.project cabal.project
       - if: runner.os == 'Windows' && matrix.ghc == '8.8.4'
         name: (Windows,GHC 8.8) Modify `cabal.project` to workaround segfaults
         run: |

.github/workflows/test.yml

@@ -95,7 +95,8 @@ jobs:
       - if: matrix.ghc == '9.0.1'
         name: (GHC 9.0.1) Use modified `cabal.project`
         run: |
-          cp cabal-ghc901.project cabal.project
+          # This seems insane, but it is needed.
+          rm -f -v cabal.project && cp -v cabal-ghc901.project cabal.project
       - if: runner.os == 'Windows' && matrix.ghc == '8.8.4'
         name: (Windows,GHC 8.8) Modify `cabal.project` to workaround segfaults
         run: |