Another attempt at being cross-platform compatible

.github/workflows/more-ci.yml

@@ -59,9 +59,9 @@ jobs:
       # we already check the build with this option in the main CI job, we
       # disable it here unconditionally for simplicity.
       - name: Edit dune-project
+        shell: pwsh
         run: |
-          sed -i.bak '/(implicit_transitive_deps false)/d' dune-project
-          rm dune-project.bak
+          (Get-Content dune-project) -notmatch '\(implicit_transitive_deps false\)' | Set-Content dune-project
 
       # We build and run tests for a subset of packages. More tests are run in
       # the development workflow and as part of the main CI job. These are the