Adds python 3.9.4 and 3.10.0a7 (#217)

* pkg(python-3.9.4): Adds python 3.9.4

* pkg(python-3.10.0a7): Adds python 3.10.0a7

* pkg(python-3.10.0a7): More pythonic 3.10.0a7 code

* pkg(python-3.10.0a7): Use semver versioning

* pkg(python-3.10.0a7): remove 'py3' alias and add 'py'

* pkg(python-3.9.4): remove 'py3' alias and add 'py'

packages/python/3.9.4/build.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+PREFIX=$(realpath $(dirname $0))
+
+mkdir -p build
+
+cd build
+
+curl "https://www.python.org/ftp/python/3.9.4/Python-3.9.4.tgz" -o python.tar.gz
+tar xzf python.tar.gz --strip-components=1
+rm python.tar.gz
+
+./configure --prefix "$PREFIX" --with-ensurepip=install
+make -j$(nproc)
+make install -j$(nproc)
+
+cd ..
+
+rm -rf build 
+
+bin/pip3 install numpy scipy pandas pycrypto whoosh bcrypt passlib