package/python-pillow: bump to version 8.0.1

package/python-pillow: bump to version 8.0.1

Bumping the package requires two fixes:
* pillow looks for header files in paths returned by pkg-config.
  On buildroot, pkg-config returns nothing if PKG_CONFIG_ALLOW_SYSTEM_CFLAGS
  is disabled.
* png is the default pillow image format and png format is working only
  if python zlib module is available.

Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com>
Tested-by: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>