Openepd

Fix

- add commit to test versioning

Fix

- correct content and docs of Concrete exposure classes enums

Feat

- add more specs for materials
- add logic for replacing Impacts LCIA method

Refactor

- extract semantic types for pydantic models

Fix

- correct conditional quantity validator

Feat

- support external quantity validators
- map models for Steel and Concrete

Feat

- implement factory function for EPD
- change spec structure to nested
- add `openepd_version` to EPD
- add material spec versions
- add initial specs named after categories
- add Readme on versioning specs

Fix

- add test action
- fix broken tests

Refactor

- generalize versions for other document types
- split validation to numbers and common