I've fiddled/struggled with this by myself, by getting a permission error like this one:
```shell
OutputFileAccessError: Output file location (./output.pdf) is not a writable file.
```
I've loosely followed and found https://github.com/containers/podlet?tab=readme-ov-file#in-a-container and explained the required flags in a similar way, but adapted for this tool (it likely won't be used so much on system files).
I've tested it and it works fine for me. The same issue may be on Docker rootless, but I guess people will get that and I cannot test it here.
strip_invisible_text resets the text render mode on each `BT` (begin text) command. However the text state is not actually reset for each text element, only for each page.
The pdf reference says:
> The text state operators can appear outside text objects, and the values they set
> are retained across text objects in a single content stream. Like other graphics
> state parameters, these parameters are initialized to their default values at the
> beginning of each page.
>
> -- https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/pdfreference1.7old.pdf#page=397
With the current implementation, a text object is only deleted if it contains a `3 Tr` command (setting the text rendering mode to invalid). However the rendering mode may be set once and then not changed for multiple text objects or set outside of a text object.
In that case only the first text object (which contains the `3 Tr`-command) is removed. This not only leaves the other text objects in the pdf, but also makes them visible, since the text object that contained the `3 Tr`-command is removed.
This PR updates `strip_invisible_text` to not reset the rendering mode for each object and to keep track of the rendering mode when the graphic state is pushed/popped.