Use pypi PURLs instead of plain pypi names

This allows us to include a version and we already use PURL
for other things, so might as well remove the pypi special case.

Normalize the names, since that is required for PURLs.

python-typogrify/PKGBUILD

@@ -8,7 +8,7 @@ pkgdesc='filters to make caring about typography on the web a bit easier'
 arch=('any')
 url='https://github.com/justinmayer/typogrify'
 msys2_references=(
-  'pypi: typogrify'
+  'purl: pkg:pypi/typogrify'
 )
 license=('spdx:BSD-3-Clause')
 depends=('python' 'python-smartypants')