Ormsgpack

Misc
- Refactored adding objects to the module, creating a `__all__` object similar to the way PyO3 creates. This solves an issue with upgrading to new maturin version.
- Changed < Py3.7 implementation to use automatic range inclusion.
- Added test to validate correct Python method flags are used on declare.
- Changed to use PyO3 configurations instead of our own. PR [25](/../../pull/25) by [pejter](https://github.com/pejter).

Fixed
- Fix memory leak serializing `datetime.datetime` with `tzinfo`. (Copied from orjson)
Changed
- Update dependencies, PyO3 -> 0.14.1.
Misc
- Setup dependabot.

Changed
- `packb` of maps and sequences is now almost 2x faster as it leverages known size. PR [18](/../../pull/18) by [ijl](https://github.com/ijl).
Misc
- Added `scripts/bench_target.py` and `scripts/profile.sh` for easily benchmarking and profiling. Works only on Linux. PR [17](/../../pull/17) by [ijl](https://github.com/ijl).

Added
- `unpackb` now accepts keyword argument `option` with argument `OPT_NON_STR_KEYS`. This option will let ormsgpack
unpack dictionaries with non-str keys.
Be aware that this option is considered unsafe and disabled by default in msgpack due to possibility of HashDoS.
- `packb` now is able to pack dictionaries with tuples as keys. `unpackb` is able to unpack such dictionaries. Both requires
`OPT_NON_STR_KEYS`.
Misc
- Grouped benchmarks in a pattern that should make more sense.
- Added pydantic docs to `README.md`
- Added graphs and benchmark results.

Fixed
- Depth limit is now enforced for `ormsgpack.unpackb` - function should be safe for use now.
Removed
- Removed `OPT_SERIALIZE_UUID` from ormsgpack.pyi as it doesn't exist.
Misc
- Added `scripts/test.sh` for running tests.
- Added benchmarks, modified scripts to match new layout.

Added
- Add support for serializing pydantic's `BaseModel` instances using `ormsgpack.OPT_SERIALIZE_PYDANTIC`.
Fixed
- `ormsgpack.packb` with `option` argument as `ormsgpack.OPT_NON_STR_KEYS` serializes bytes key into tuple of integers
instead of using bin type. This also resulted in asymmetrical packb/unpackb.
Misc
- Added `--no-index` to `pip install ormsgpack` to avoid installing from PyPI on CI.