Specfile

- It is now possible to filter changelog entries by specifying lower bound EVR, upper bound EVR or both. (104)
- Added support for filenames specified in source URL fragments, for example: `https://example.com/foo/1.0/download.cgi#/%{name}-%{version}.tar.gz` (100)

- Switched to our own implementation of working with `%changelog` timestamps and removed dependency on arrow (88)
- Fixed requires of EPEL 8 rpm (86)

- Added new `%conf` section (74)
- Switched to rpm-py-installer (75)
- Fixed detecting extended timestamp format in `%changelog` (77, 81)

- Strict optional typing is now enforced (68)
- Fixed deduplication of tag names (69)
- Sources and patches can now be removed by number (69)
- Number of digits in a source number is now expressed the same way as packit does it (69)
- Empty lines are now compressed when deleting tags (69)
- Added convenience property for getting texts of tag comments (69)
- Added convenience method for adding a patch (69)

- Added convenience properties for most used tags (63)
- Hardened linting by ignoring only specific mypy errors (64)
- Fixed list of valid tag names and ensured newly added tags are not part of a condition block (66)
- Initial patch number and its default number of digits are now honored (66)
- Fixed a bug in `%prep` macro stringification (67)

- Made `Sources` a `MutableSequence` (36)
- Started using consistent terminology for source numbers and added the option to insert a source with a specific number (47)
- Added support for implicit source numbering (48)
- Documented sources and `%prep` macros in README (49)
- Implemented high-level manipulation of version and release (54)
- Added support for `%autochangelog` (56)
- Added `remote` property to sources and enabled addition of `Sources` (59)
- Implemented mid-level manipulation of `%prep` section, including modification of `%prep` macros (37, 52)