Docs: Update minimum Python version. Add matching badge (#226)

Author: moreati

README.rst

@@ -6,6 +6,10 @@ pyperf
    :alt: Latest release on the Python Cheeseshop (PyPI)
    :target: https://pypi.python.org/pypi/pyperf
 
+.. image:: https://img.shields.io/python/required-version-toml?tomlFilePath=https%3A%2F%2Fraw.githubusercontent.com%2Fpsf%2Fpyperf%2Frefs%2Fheads%2Fmain%2Fpyproject.toml
+   :alt: Supported Python versions
+   :target: https://pypi.python.org/pypi/pyperf
+
 .. image:: https://github.com/psf/pyperf/actions/workflows/build.yml/badge.svg
    :alt: Build status of pyperf on GitHub Actions
    :target: https://github.com/psf/pyperf/actions
@@ -128,7 +132,7 @@ Command to install pyperf on Python 3::
 
     python3 -m pip install pyperf
 
-pyperf requires Python 3.7 or newer.
+pyperf requires Python 3.9 or newer.
 
 Python 2.7 users can use pyperf 1.7.1 which is the last version compatible with
 Python 2.7.

doc/run_benchmark.rst

@@ -23,7 +23,7 @@ Optional dependencies:
 * Python module ``psutil``. Install: ``python3 -m pip install -U psutil``.
 * When you are using macOS, you need to install ``psutil`` if you want to use ``--track-memory`` option.
 
-pyperf requires Python 3.6 or newer.
+pyperf requires Python 3.9 or newer.
 
 Python 2.7 users can use pyperf 1.7.1 which is the last version compatible with
 Python 2.7.

pyproject.toml

@@ -44,6 +44,7 @@ classifiers = [
     "Programming Language :: Python :: 3",
     "Topic :: Software Development :: Libraries :: Python Modules"
 ]
+# Also update: README.rst, docs/run_benchmark.rst
 requires-python = ">=3.9"
 dependencies = ["psutil>=5.9.0"]