tempfiles are not removed

using this package you'll collect _a lot_ of tempfiles

the unit-test for example (reading iptc once, and writing on image save) produces 3 temporary files

```
76332 Jun 17 11:55 tmpoTle9a_sample.jpg
76270 Jun 17 11:55 tmpoTle9a_sample.jpg~
76270 Jun 17 11:55 tmpyDbD2n_sample.jpg
```

check if temporary files are really necessary. if they are, they should be cleaned up

Start by running the unit test described in the issue, which reads IPTC metadata once and writes the image on save, then inspect where its three temporary files are created. Determine whether those files are necessary; done means necessary temporary files are cleaned up and the test no longer leaves them behind.

Written by the indexing model from the issue text.