Lmdb

* CI-only fix.

* Add Python 3.12 binaries.

* Update bundled LMDB to 0.9.31.

* Remove Python 2.7 support.

* Update CI to build manylinux binaries.

* Add Python 3.11 support.

* Add aarch64 architecture builds. Contributed by odidev.

* Add Python 3.10 support.

* Fix crash relating to caching of transactions. The 'max_spare_txns'
parameter to Environment/open is currently ignored.

* Resolve CI bug where non-Linux wheels were not being published to PyPI.