Remove deprecation warning ('cachedir' parameter has been deprecated)

Warning was:

```
  /localhome/seitz_local/projects/pystencils/pystencils/cache.py:15: DeprecationWarning: The 'cachedir' parameter has been deprecated in
version 0.12 and will be removed in version 0.14.
  You provided "cachedir='/localhome/seitz_local/.cache/pystencils'", use "location='/localhome/seitz_local/.cache/pystencils'" instead.
    disk_cache = Memory(cachedir=cache_dir, verbose=False).cache
```
6 jobs for remove-deprecation-warning-cachedir in 3 minutes and 43 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
passed #287753
cuda docker
build-documentation

00:00:35

passed #287752
cuda docker
flake8-lint

00:00:19

passed #287751
docker
minimal-conda

00:00:21

passed #287750
docker
minimal-ubuntu

00:00:22

passed #287749
win
minimal-windows

00:01:37

passed #287748
AVX cuda docker
tests-and-coverage

00:03:38