feat: add CPython 3.10 pre-release support (#675)

* Add CPython 3.10 support

* Fix logger displaying CPython 3.1 instead of 3.10

* Fix tests failing with CPython 3.10

* Use pytest instead of nose

* feat: --pre flag

Apply suggestions from code review

Co-authored-by: Matthieu Darbois <mayeut@users.noreply.github.com>

* fix: update Python update script to process beta versions

* refactor: prerelease-pythons

* Use `strtobool` to parse `CIBW_PRERELEASE_PYTHONS` env var

* Update python version filtering for universal2 & arm64

* Filter out CPython 3.10 and above for `test_manylinuxXXXX_only[manylinux1]` test

* Use CIBW_BUILD filtering rather than CIBW_SKIP for test_docker_images

* Use skip_patterns to filter out pre-releases

* Use `prerelease_pythons` instead of `pre`

* Reword `CIBW_PRERELEASE_PYTHONS` doc per review.

* Use `CIBW_PRERELEASE_PYTHONS: True` for usage example.

* Update `cibuildwheel --help` doc

* docs: add note on spec.filter

* Clean up the BuildSelector __repr__ by refactoring

* fix: remove platform variants for CIBW_PRERELEASE_PYTHONS

* docs: mention the flag

Co-authored-by: Henry Schreiner <henryschreineriii@gmail.com>
Co-authored-by: Joe Rickerby <joerick@mac.com>

docs/options.md

@@ -299,6 +299,32 @@ the package is compatible with all versions of Python that it can build.
 CIBW_PROJECT_REQUIRES_PYTHON: ">=3.6"
 ```
 
+###  `CIBW_PRERELEASE_PYTHONS` {: #prerelease-pythons}
+> Enable building with pre-release versions of Python
+
+During the beta period, when new versions of Python are being tested,
+cibuildwheel will often gain early support for beta releases. If you would
+like to test wheel building with these versions, you can enable this flag.
+
+!!! caution
+    This option is provided for testing purposes only. It is not
+    recommended to distribute wheels built when `CIBW_PRERELEASE_PYTHONS` is
+    set, such as uploading to PyPI.  Please _do not_ upload these wheels to
+    PyPI, as they are not guaranteed to work with the final Python release.
+    Once Python is ABI stable and enters the release candidate phase, that
+    version of Python will become available without this flag.
+
+Default: Off (0) if Python is available in beta phase. No effect otherwise.
+
+This option can also be set using the [command-line option](#command-line) `--prerelease-pythons`.
+
+#### Examples
+
+```yaml
+# Include latest Python beta
+CIBW_PRERELEASE_PYTHONS: True
+```
+
 ## Build customization
 
 ### `CIBW_ENVIRONMENT` {: #environment}
@@ -715,6 +741,7 @@ CIBW_BUILD_VERBOSITY: 1
 usage: cibuildwheel [-h] [--platform {auto,linux,macos,windows}]
                     [--archs ARCHS] [--output-dir OUTPUT_DIR]
                     [--print-build-identifiers] [--allow-empty]
+                    [--prerelease-pythons]
                     [package_dir]
 
 Build wheels for all the platforms.
@@ -741,8 +768,8 @@ optional arguments:
                         natively supported on this machine. Set this option to
                         build an architecture via emulation, for example,
                         using binfmt_misc and QEMU. Default: auto. Choices:
-                        auto, native, all, x86_64, i686, aarch64, ppc64le,
-                        s390x, x86, AMD64
+                        auto, auto64, auto32, native, all, x86_64, i686,
+                        aarch64, ppc64le, s390x, universal2, arm64, x86, AMD64
   --output-dir OUTPUT_DIR
                         Destination folder for the wheels.
   --print-build-identifiers
@@ -750,6 +777,7 @@ optional arguments:
                         invocation and exit.
   --allow-empty         Do not report an error code if the build does not
                         match any wheels.
+  --prerelease-pythons  Enable pre-release Python versions if available.
 ```
 
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