community/py3-pypng: copy license to package

Add special handling for MIT as required by
https://wiki.alpinelinux.org/wiki/Creating_an_Alpine_package#license

community/py3-pypng/APKBUILD

 # Maintainer: Marian Buschsieweke <marian.buschsieweke@posteo.net>
 pkgname=py3-pypng
 pkgver=0.0.20
-pkgrel=5
+pkgrel=6
 pkgdesc="Pure Python PNG image encoder/decoder"
 url="https://github.com/drj11/pypng"
 arch="noarch"
@@ -27,6 +27,8 @@ check() {
 
 package() {
 	python3 setup.py install --skip-build --root="$pkgdir"
+
+	install -Dm644 LICENCE "$pkgdir"/usr/share/licenses/$pkgname/LICENSE
 }
 sha512sums="
 4f84e9b9cc68c0ad7e4558f0f46c54b0f091561f1a3679ac0679d8a1f1ab9a06493d71bf9df4db5deb6bedbdfa53bb1775ee51204133309eba962077102fdcdd  pypng-0.0.20.tar.gz