Updated versioneer and removed some Python 2 and 3.6 support.

Makefile

@@ -14,7 +14,7 @@ help:
 
 conda:  # Set up a conda environment for development.
 	@printf "Creating conda environment...\n"
-	${CONDA} create --yes --name ${PROJECT_NAME}-env python=3.6
+	${CONDA} create --yes --name ${PROJECT_NAME}-env python=3.9
 	( \
 	${CONDA} activate ${PROJECT_NAME}-env; \
 	${PIP} install -U pip; \

aesara/tensor/blas_c.py

-# import aesara.tensor.basic as aet
-
 from aesara.configdefaults import config
 from aesara.graph.op import COp
 from aesara.graph.opt import in2out
 from aesara.graph.params_type import ParamsType
 from aesara.scalar import bool as bool_t
-
-# Work-around for Python 3.6 issue that prevents `import aesara.tensor as aet`
 from aesara.tensor import basic as aet
 from aesara.tensor.blas import (
     Gemv,

aesara/tensor/nnet/basic.py

@@ -28,8 +28,6 @@ from aesara.graph.op import COp, Op
 from aesara.graph.opt import copy_stack_trace, local_optimizer, optimizer
 from aesara.raise_op import Assert
 from aesara.scalar import UnaryScalarOp
-
-# Work-around for Python 3.6 issue that prevents `import aesara.tensor as aet`
 from aesara.tensor import basic as aet
 from aesara.tensor import extra_ops, math_opt
 from aesara.tensor.basic import ARange, as_tensor_variable

aesara/tensor/var.py

@@ -50,10 +50,6 @@ class _tensor_py_operators:
         rval._is_nonzero = False
         return rval
 
-    def __nonzero__(self):
-        # Python 2.x
-        return self.__bool__()
-
     def __bool__(self):
         # This is meant to prohibit stuff like a < b < c, which is internally
         # implemented as (a < b) and (b < c). The trouble with this is the

doc/requirements.inc

@@ -15,15 +15,16 @@ Requirements
 .. _skcuda: http://scikit-cuda.readthedocs.io/en/latest/
 .. _warp-ctc: https://github.com/baidu-research/warp-ctc
 
-    Python_ == 2.7* or ( >= 3.4 and < 3.6 )
+    Python_ == >= 3.7
         |PythonDistRecommended|. Python 2.4 was supported up to and including the
         release 0.6. Python 2.6 was supported up to and including the
         release 0.8.2. Python 3.3 was supported up to and including release 0.9.
+        Python 3.6 was supported up to and including release 2.3.4.
 
-    `NumPy <http://numpy.scipy.org/>`_ >= 1.9.1 <= 1.12
+    `NumPy <http://numpy.scipy.org/>`_ >= 1.9.1
         Earlier versions could work, but we don’t test it.
 
-    `SciPy <http://scipy.org>`_ >= 0.14 < 0.17.1
+    `SciPy <http://scipy.org>`_ >= 0.14
         Only currently required for sparse matrix and special functions support, but highly recommended. SciPy >=0.8 could work, but earlier versions have known bugs with sparse matrices.
 
     `BLAS`_ installation (with Level 3 functionality)

doc/tutorial/debug_faq.rst

@@ -360,7 +360,6 @@ shows how to print all inputs and outputs:
 
 .. testcode::
 
-    from __future__ import print_function
     import aesara
 
     def inspect_inputs(fgraph, i, node, fn):

doc/tutorial/examples.rst

@@ -460,7 +460,6 @@ corresponding to the random number generation process (i.e. RandomFunction{unifo
 An example of how "random states" can be transferred from one aesara function
 to another is shown below.
 
->>> from __future__ import print_function
 >>> import aesara
 >>> import numpy
 >>> import aesara.tensor as aet

requirements.txt

 -e ./
-dataclasses>=0.7; python_version < '3.7'
 filelock
-flake8==3.8.4
+flake8>=3.8.4
 pep8
 pyflakes
-black==20.8b1; platform.python_implementation!='PyPy'
+black>=20.8b1
 pytest-cov>=2.6.1
 coverage>=5.1
 pytest
@@ -12,8 +11,8 @@ coveralls
 cython
 sympy
 versioneer
-jax; python_version > '3.6'
-jaxlib; python_version > '3.6'
+jax
+jaxlib
 numba
 numba-scipy>=0.3.0
 diff-cover

setup.py

 #!/usr/bin/env python
 import os
-import sys
 
 from setuptools import find_packages, setup
 
@@ -39,7 +38,6 @@ Operating System :: POSIX
 Operating System :: Unix
 Operating System :: MacOS
 Programming Language :: Python :: 3
-Programming Language :: Python :: 3.6
 Programming Language :: Python :: 3.7
 Programming Language :: Python :: 3.8
 Programming Language :: Python :: 3.9
@@ -57,9 +55,6 @@ install_requires = [
 ]
 
 
-if sys.version_info[0:2] < (3, 7):
-    install_requires += ["dataclasses"]
-
 # Handle builds of nightly release
 if "BUILD_AESARA_NIGHTLY" in os.environ:
     nightly = True