Update pillow to 8.1.0

[pyup-bot]

This PR updates pillow from 8.0.1 to 8.1.0.

Changelog

### 8.1.0 ``` ------------------ - Fix TIFF OOB Write error. CVE-2020-35654 5175 [wiredfool] - Fix for Read Overflow in PCX Decoding. CVE-2020-35653 5174 [wiredfool, radarhere] - Fix for SGI Decode buffer overrun. CVE-2020-35655 5173 [wiredfool, radarhere] - Fix OOB Read when saving GIF of xsize=1 5149 [wiredfool] - Makefile updates 5159 [wiredfool, radarhere] - Add support for PySide6 5161 [hugovk] - Use disposal settings from previous frame in APNG 5126 [radarhere] - Added exception explaining that _repr_png_ saves to PNG 5139 [radarhere] - Use previous disposal method in GIF load_end 5125 [radarhere] - Allow putpalette to accept 1024 integers to include alpha values 5089 [radarhere] - Fix OOB Read when writing TIFF with custom Metadata 5148 [wiredfool] - Added append_images support for ICO 4568 [ziplantil, radarhere] - Block TIFFTAG_SUBIFD 5120 [radarhere] - Fixed dereferencing potential null pointers 5108, 5111 [cgohlke, radarhere] - Deprecate FreeType 2.7 5098 [hugovk, radarhere] - Moved warning to end of execution 4965 [radarhere] - Removed unused fromstring and tostring C methods 5026 [radarhere] - init() if one of the formats is unrecognised 5037 [radarhere] - Moved string_dimension CVE image to pillow-depends 4993 [radarhere] - Support raw rgba8888 for DDS 4760 [qiankanglai] ```

Links

- PyPI: https://pypi.org/project/pillow - Changelog: https://pyup.io/changelogs/pillow/ - Homepage: https://python-pillow.org

[duckinator]

bors r+

[bors[bot]]

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