CI: Fix Cygwin Cache

[kit-ty-kate]

Extracted from #5171

Fixes the following failure in the Windows CI (the non-cygwin runs):

[...]
+ git clean -dfX
Removing 0.40.tar.gz
Removing Makefile.config
Removing _build/
+ [[ -n master ]]
Removing config.log
+ git checkout combak
Removing config.status
Removing ocaml-4.13.1.tar.gz
Removing opam-installer.exe
Removing opam-installer.install
Removing opam.exe
Removing opam.install
Removing processed-opam-installer.install
Removing processed-opam.install
Removing src/ocaml-flags-configure.sexp
Removing src/stubs/c-flags.sexp
Removing src/stubs/libacl/c-libraries.sexp
Removing src/stubs/win32/cc64
Removing src/stubs/win32/dune
Removing src_ext/0install-solver.download
Removing src_ext/0install-solver.pkgdownload
Removing src_ext/0install-solver.stamp
Removing src_ext/0install-solver.tbz
Removing src_ext/0install-solver/
Removing src_ext/archives/
Removing src_ext/base64.download
Removing src_ext/base64.pkgdownload
Removing src_ext/base64.stamp
Removing src_ext/base64.tbz
Removing src_ext/base64/
Removing src_ext/cmdliner.download
Removing src_ext/cmdliner.pkgdownload
Removing src_ext/cmdliner.stamp
Removing src_ext/cmdliner.tbz
Removing src_ext/cmdliner/
Removing src_ext/cppo.download
Removing src_ext/cppo.pkgdownload
Removing src_ext/cppo.stamp
Removing src_ext/cppo.tar.gz
Removing src_ext/cppo/
Removing src_ext/cudf.download
Removing src_ext/cudf.pkgdownload
Removing src_ext/cudf.stamp
Removing src_ext/cudf.tar.gz
Removing src_ext/cudf/
Removing src_ext/dose3.download
Removing src_ext/dose3.pkgdownload
Removing src_ext/dose3.stamp
Removing src_ext/dose3.tar.gz
Removing src_ext/dose3/
Removing src_ext/dune
Removing src_ext/dune-local.download
Removing src_ext/dune-local.pkgdownload
Removing src_ext/dune-local.stamp
Removing src_ext/dune-local.tbz
Removing src_ext/dune-local/
Removing src_ext/extlib.download
Removing src_ext/extlib.pkgdownload
Removing src_ext/extlib.stamp
Removing src_ext/extlib.tar.gz
Removing src_ext/extlib/
Removing src_ext/jsonm.download
Removing src_ext/jsonm.pkgdownload
Removing src_ext/jsonm.stamp
Removing src_ext/jsonm.tbz
Removing src_ext/jsonm/
Removing src_ext/mccs.download
Removing src_ext/mccs.pkgdownload
Removing src_ext/mccs.stamp
Removing src_ext/mccs.tar.gz
Removing src_ext/mccs/
Removing src_ext/ocamlgraph.download
Removing src_ext/ocamlgraph.pkgdownload
Removing src_ext/ocamlgraph.stamp
Removing src_ext/ocamlgraph.tbz
Removing src_ext/ocamlgraph/
Removing src_ext/opam-0install-cudf.download
Removing src_ext/opam-0install-cudf.pkgdownload
Removing src_ext/opam-0install-cudf.stamp
Removing src_ext/opam-0install-cudf.tbz
Removing src_ext/opam-0install-cudf/
Removing src_ext/opam-file-format.download
Removing src_ext/opam-file-format.pkgdownload
Removing src_ext/opam-file-format.stamp
Removing src_ext/opam-file-format.tar.gz
Removing src_ext/opam-file-format/
Removing src_ext/re.download
Removing src_ext/re.pkgdownload
Removing src_ext/re.stamp
Removing src_ext/re.tbz
Removing src_ext/re/
Removing src_ext/result.download
Removing src_ext/result.pkgdownload
Removing src_ext/result.stamp
Removing src_ext/result.tbz
Removing src_ext/result/
Removing src_ext/seq.download
Removing src_ext/seq.pkgdownload
Removing src_ext/seq.stamp
Removing src_ext/seq.tar.gz
Removing src_ext/seq/
Removing src_ext/sha.download
Removing src_ext/sha.pkgdownload
Removing src_ext/sha.stamp
Removing src_ext/sha.tbz
Removing src_ext/sha/
Removing src_ext/spdx_licenses.download
Removing src_ext/spdx_licenses.pkgdownload
Removing src_ext/spdx_licenses.stamp
Removing src_ext/spdx_licenses.tbz
Removing src_ext/spdx_licenses/
Removing src_ext/stdlib-shims.download
Removing src_ext/stdlib-shims.pkgdownload
Removing src_ext/stdlib-shims.stamp
Removing src_ext/stdlib-shims.tbz
Removing src_ext/stdlib-shims/
Removing src_ext/uutf.download
Removing src_ext/uutf.pkgdownload
Removing src_ext/uutf.stamp
Removing src_ext/uutf.tbz
Removing src_ext/uutf/
error: Your local changes to the following files would be overwritten by checkout:
	doc/man/opam-topics.inc
Please commit your changes or stash them before you switch branches.
Aborting

[dra27]

LGTM! Thanks for the co-working with this 🙂

[rjbou]

thanks!