Add support for Python 3.5.10 (#1062)

Since it was released over the weekend:
https://www.python.org/downloads/release/python-3510/
https://docs.python.org/3.5/whatsnew/changelog.html#python-3-5-10

Closes @W-7835961@.

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Python 3.5.10 is now available (CPython) (#1062).
 
 ## v177 (2020-08-18)
 

bin/default_pythons

@@ -9,7 +9,7 @@ DEFAULT_PYTHON_VERSION="python-3.6.12"
 LATEST_38="python-3.8.5"
 LATEST_37="python-3.7.9"
 LATEST_36="python-3.6.12"
-LATEST_35="python-3.5.9"
+LATEST_35="python-3.5.10"
 LATEST_34="python-3.4.10"
 LATEST_27="python-2.7.18"
 LATEST_PYPY_36="pypy3.6-7.3.1"

builds/runtimes/python-3.5.10

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+# Build Path: /app/.heroku/python/
+
+source $(dirname $0)/python3

test/fixtures/python3_5/runtime.txt

@@ -1 +1 @@
-python-3.5.9
+python-3.5.10