Enables retrieval of "/Count" attribute of outline item in PdfReader.outlines by implementing property outline_count.

Closes #1122

We value the work of our contributors - of all of them. The CONTRIBUTORS file might give them more visibility and be more robust when the project is vendored into other projects.

It is by far not complete - I hope that people add themselves in PRs :-) 

See #798

There were typos in:
- docs/meta/project-governance.md
- tests/test_reader.py
- tests/test_writer.py

Fixes:
- Should read `inducing` rather than `indiducing`.
- Should read `decisions` rather than `decisons`.

Signed-off-by: Tim Gates <tim.gates@iress.com>

Rebuild the xref table if the parent chained xref is invalid

Closes #1089

Closes #1134

See https://docs.github.com/en/repositories/working-with-files/using-files/viewing-a-file#ignore-commits-in-the-blame-view

…3.0.0 (#1139)

Accidentally, PyPDF2 did not follow the deprecation process:
https://pypdf2.readthedocs.io/en/latest/dev/deprecations.html

ISSUE: The EncodedStreamObject.getData / setData were removed
AFFECTS: PyPDF2>=1.28.3,<=2.6.0
FIX: Add the getData / setData methods back with deprecation warnings

Closes #1138

Added /Opt to the checked field_attributes within reader.get_fields

Closes #391

New Features (ENH):
-  Add `outline_count` property (#1129)

Bug Fixes (BUG):
-  Make reader.get_fields also return dropdowns with options (#1114)
-  Add deprecated EncodedStreamObject functions back until PyPDF2==3.0.0 (#1139)

Robustness (ROB):
-  Cope with missing /W entry (#1136)
-  Cope with invalid parent xref (#1133)

Documentation (DOC):
-  Contributors file (#1132)
-  Fix type in signature of PdfWriter.add_uri (#1131)

Developer Experience (DEV):
-  Add .git-blame-ignore-revs (#1141)

Code Style (STY):
-  Fixing typos (#1137)
-  Re-use code via get_outlines_property in tests (#1130)

Full Changelog: 2.6.0...2.7.0