main/subunit: fix shebang lines

Before this change:

    $ dabuild sh
    $ sudo apk add subunit >/dev/null && subunit-stats --help
    env: can't execute 'python': No such file or directory

After this change:

    $ dabuild sh
    $ sudo apk add subunit >/dev/null && subunit-stats --help
    Usage: subunit-stats [options]
    

main/subunit/APKBUILD

@@ -2,7 +2,7 @@
 # Maintainer: Natanael Copa <ncopa@alpinelinux.org>
 pkgname=subunit
 pkgver=1.3.0
-pkgrel=0
+pkgrel=1
 pkgdesc="A streaming protocol for test results"
 options="!check" # Dependencies for checking stuff are in testing/
 url="https://launchpad.net/subunit"
@@ -40,6 +40,7 @@ package() {
 	make DESTDIR="$pkgdir" install
 	find "$pkgdir" \( -name perllocal.pod -o -name .packlist \) -delete
 	rm -f "$pkgdir"/usr/lib/*.a
+	sed -i '1s|/usr/bin/env python$|/usr/bin/python3|' "$pkgdir"/usr/bin/*
 }
 
 sha512sums="7b37890546345cc481779f4bf1dc7eeca4fbda0efff1b7d7a6ca7ec574fe72e9801b7b70b8efcb0d78bb6a0a181fcdb6e49a2ff280d73f0d3dfcd1df219b2765  subunit-1.3.0.tar.gz"