Adding initial 3.12 support

tox.ini

@@ -1,14 +1,14 @@
 [tox]
 skipsdist = true
-envlist = py{37,38,39,310,311}, flake8, dist, manifest, docs, binder
+envlist = py{38,39,310,311,312}, flake8, dist, manifest, docs, binder
 
 [gh-actions]
 python =
-    3.7: py37
-    3.8: py38, dist
+    3.8: py38
     3.9: py39
     3.10: py310
     3.11: py311
+    3.12: py312, dist
 
 # Linters
 [testenv:flake8]
@@ -47,6 +47,7 @@ commands = python -c "import glob; import papermill as pm; [pm.execute_notebook(
 [testenv:dist]
 skip_install = true
 # Have to use /bin/bash or the `*` will cause that argument to get quoted by the tox command line...
+allowlist_externals = /bin/bash
 commands =
     python setup.py sdist --dist-dir={distdir} bdist_wheel --dist-dir={distdir}
     /bin/bash -c 'python -m pip install -U --force-reinstall {distdir}/papermill*.whl'
@@ -55,7 +56,7 @@ commands =
 # Black
 [testenv:black]
 description = apply black linter with desired rules
-basepython = python3.8
+basepython = python3.12
 deps =
     black
 commands = black -S -l 100 .
@@ -68,16 +69,18 @@ setenv =
     AWS_SECRET_ACCESS_KEY=foobar_secret
 passenv = *
 basepython =
-    py37: python3.7
     py38: python3.8
     py39: python3.9
     py310: python3.10
     py311: python3.11
-    flake8: python3.8
-    manifest: python3.8
-    dist: python3.8
-    docs: python3.8
-    binder: python3.8
-    black: python3.8
+    py312: python3.12
+    flake8: python3.12
+    manifest: python3.12
+    dist: python3.12
+    docs: python3.12
+    binder: python3.12
+    black: python3.12
 deps = .[dev]
+# Python 3.12 breaks default pip/setuptools versions ... force an upgrade of these before anything else
+install_command = /bin/bash ./tox_py_installer {opts} {packages}
 commands = pytest -v --maxfail=2 --cov=papermill -W always {posargs}

tox_py_installer

@@ -0,0 +1,5 @@
+#!/bin/bash
+python -m ensurepip --upgrade
+python -m pip install --upgrade setuptools
+# python -m pip install {opts} {packages}
+python -m pip install $1 $2