chore: release 2.2.1b0

[release-please]

🤖 I have created a release *beep* *boop*

2.2.1b0 (2021-01-29)

⚠ BREAKING CHANGES

• DBAPI code was moved into python-spanner in feat: DB-API driver + unit tests python-spanner#160. This change removes it from this repo and bumps the dependency on python-spanner to 2.0.0, the first released version to include DBAPI.
• Update python-spanner dep, drop py 3.5 (refactor!: Update python-spanner dep, drop py 3.5 #557)

Features

• [WIP] The first stage of nox implementation (#468) (96f2223)
• Add dummy WHERE clause to certain statements (#516) (af5d8e3)
• add PyPI release support (#451) (da82c41)
• clear session pool on connection close (#543) (14e4cac)
• cursor must detect if the parent connection is closed (#463) (a9fd5a3)
• Implementing DB-API types according to the PEP-0249 specification (#521) (62c22b1)
• refactor connect() function, cover it with unit tests (#462) (4fedcf1)
• Stage 2 of nox implementation - adding docs target (#473) (45d6b97)
• Stage 3-4 of nox implementation - adding auto-format targets (#478) (59e7c3f)
• Stage 5 of nox implementation - adding coverage targets (#479) (cec6b96)
• Stage 6 of nox implementation - enabling system tests (#480) (dc73bf6)
• support transactions management (#535) (2f2cd86)

Bug Fixes

• add description for transaction autocommit (#587) (8441edc)
• add project env in readme file (#586) (55b9d19)
• Bump version ahead of lateset release (#571) (36e5b82)
• Change release script package name (#489) (388ea6b)
• DatabaseWrapper method impl and potential bugfix (#545) (d8453c7)
• Fix black, isort compatibility (#469) (dd005d5)
• fix from-scratch tutorial (#573) (59ce5e7)
• fix healthchecks app tutorial (#574) (65d2e9d)
• Fix license classifier (#507) (9244414)
• Fix package name in README (#556) (8b2329a)
• fix typo in README (#575) (d25fa86)
• override django autocommit to spanner (#583) (7ce685d)
• permanently broken date & time unit tests on Windows (#524) (3f5db62)
• Replace repo name with pkg name (#508) (fbba900)
• s/installation/installation/ (#509) (03c963a)
• s/useage/usage/ (#511) (6b960ec)
• update pypi package name (#454) (47154d1)
• Update README for alpha release (#503) (3d31167)
• Update version to 2.2.0a1 (#506) (a3a6344)
• Use "any" default role in sphinx (#550) (196c449)

Code Refactoring

• erase dbapi directory and all the related tests (#554) (8183247)
• Update python-spanner dep, drop py 3.5 (#557) (5910833)

Documentation

• add a querying example into the main readme (#515) (c477cc2)
• minor fixes to README.md (#448) (f969000)
• move test suite information to CONTRIBUTING.md (#442) (05280ae)
• Update docstrings for django_spanner (#564) (7083f1d)
• updated README.rst file (#563) (d70cb28)
• verify and comment the DB API exceptions (#522) (5ed0845)

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[yoshi-automation]

Release is at https://github.com/googleapis/python-spanner-django/releases/tag/v2.2.1b0