REL: 4.2.0

## What's new

### New Features (ENH)
- Allow multiple charsets for NameObject.read_from_stream (#2585) by @pubpub-zz
- Add support for /Kids in page labels (#2562) by @stefan6419846
- Allow to update fields on many pages (#2571) by @pubpub-zz
- Tolerate PDF with invalid xref pointed objects (#2335) by @pubpub-zz
- Add Enforce from PDF2.0 in viewer_preferences (#2511) by @pubpub-zz
- Add += and -= operators to ArrayObject (#2510) by @pubpub-zz

### Bug Fixes (BUG)
- Fix merge_page sometimes generating unknown operator 'QQ' (#2588) by @rfotino
- Fix fields update where annotations are kids of field (#2570) by @pubpub-zz
- Process CMYK images without a filter correctly (#2557) by @pubpub-zz
- Extract text in layout mode without finding resources (#2555) by @pubpub-zz
- Prevent recursive loop in some PDF files (#2505) by @pubpub-zz

### Robustness (ROB)
- Tolerate "truncated" xref (#2580) by @pubpub-zz
- Replace error by warning for EOD in RunLengthDecode/ASCIIHexDecode (#2334) by @pubpub-zz
- Rebuild xref table if one entry is invalid (#2528) by @pubpub-zz
- Robustify stream extraction (#2526) by @pubpub-zz

### Documentation (DOC)
- Update release process for latest changes (#2564) by @stefan6419846
- Encryption/decryption: Clone document instead of copying all pages (#2546) by @redfast00
- Minor improvements (#2542) by @j-t-1
- Update annotation list (#2534) by @j-t-1
- Update references and formatting (#2529) by @j-t-1
- Correct threads reference, plus minor changes (#2521) by @j-t-1
- Minor readability increases (#2515) by @j-t-1
- Simplify PaperSize examples (#2504) by @j-t-1
- Minor improvements (#2501) by @j-t-1

### Developer Experience (DEV)
- Remove unused dependencies (#2572) by @stefan6419846
- Remove page labels PR link from message (#2561) by @stefan6419846
- Fix changelog generator regarding whitespace and handling of "Other" group (#2492) by @stefan6419846
- Add REL to known PR prefixes (#2554) by @stefan6419846
- Release using the REL commit instead of git tag (#2500) by @MartinThoma
- Unify code between PdfReader and PdfWriter (#2497) by @pubpub-zz
- Bump softprops/action-gh-release from 1 to 2 (#2514) by @dependabot[bot]

### Maintenance (MAINT)
- Ressources → Resources (and internal name childs) (#2550) by @pubpub-zz
- Fix typos found by codespell (#2549) by @stefan6419846
- Update Read the Docs configuration (#2538) by @j-t-1
- Add root_object, _info and _ID to PdfReader (#2495) by @pubpub-zz

### Testing (TST)
- Allow loading truncated images if required (#2586) by @stefan6419846
- Fix download issues from #2562 (#2578) by @pubpub-zz
- Improve test_get_contents_from_nullobject to show real use-case (#2524) by @stefan6419846
- Add missing test annotations (#2507) by @stefan6419846

[Full Changelog](4.1.0...4.2.0)