python3-pip: update to 20.3.1.

Also remove alternative and add a conflict with python-pip for
consistency with other py2 packages that have been dropped.

srcpkgs/python3-pip/template

@@ -1,6 +1,6 @@
 # Template file for 'python3-pip'
 pkgname=python3-pip
-version=20.2.4
+version=20.3.1
 revision=1
 wrksrc="pip-${version}"
 build_style=python3-module
@@ -12,10 +12,9 @@ license="MIT"
 homepage="https://pip.pypa.io/"
 changelog="https://raw.githubusercontent.com/pypa/pip/master/NEWS.rst"
 distfiles="${PYPI_SITE}/p/pip/pip-${version}.tar.gz"
-checksum=85c99a857ea0fb0aedf23833d9be5c40cf253fe24443f0829c7b472e23c364a1
-alternatives="pip:pip:/usr/bin/pip3"
+checksum=43f7d3811f05db95809d39515a5111dd05994965d870178a4fe10d5482f9d2e2
+conflicts="python-pip>=0"
 
 post_install() {
-	mv $DESTDIR/usr/bin/pip $DESTDIR/usr/bin/pip3
 	vlicense LICENSE.txt
 }