Bump pillow from 7.0.0 to 8.1.1 in /src

Bumps [pillow](https://github.com/python-pillow/Pillow) from 7.0.0 to 8.1.1.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](python-pillow/Pillow@7.0.0...8.1.1)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

src/requirements.txt

@@ -6,7 +6,7 @@ pywin32==227; platform_system == "Windows"
 PyObjC; platform_system == "darwin"
 uflash==1.3.0
 adafruit-circuitpython-fancyled==1.3.3
-Pillow==7.0.0
+Pillow==8.1.1
 adafruit-circuitpython-bitmap_font==1.1.0
 adafruit-circuitpython-display-shapes==1.2.0
 adafruit-circuitpython-neopixel==5.0.0