Casparser-isin

- support for using custom isin database via `CASPARSER_ISIN_DB` environment variable.
- updated isin.db
- packaging fixes

- DB updates
- Essel mutual funds have been renamed to NAVI
- Dividend options of funds renamed as IDCW

- updated isin.db
- updated dependent package versions

- Switch to calendar versioning
- Fix bugs with version comparison in cli update tool
- DB files are hosted in CDN for more frequent updates via CLI. [pypi releases will be limited to major changes in codebase]