chore: bump version to 2.2.0

[JeanExtreme002]

Why is this PR necessary, what does it do?

Bumps __version__ to 2.2.0 for the four changes that have landed since the
2.1.0 bump (#81):

#82	report an exited target once instead of spamming error dialogs
#84	stop the process-list refresh from stomping on scroll position and typed input
#88	macOS: let a scan walk past a page whose pager declines to read
#87	infer the byte-array scan width from the value entered (closes #79)

Minor rather than patch, because #87 is not only a fix. Alongside closing
#79 it adds a capability that did not exist in any form: an IDA pattern is a
usable cheat-table entry type, and its ? wildcard means "keep the byte that is
already there" on a write, so 48 8B ? ? 90 patches one byte and leaves the
operands alone. It also changes behaviour users will notice — the Length field
became a read-only readout for the value-sized types, an empty text value is
refused instead of scanning for NUL bytes, and "Increased/Decreased Value By" is
refused for String / Byte Array instead of silently dropping every address.

That matches the precedent for 2.1.0 itself, which was a minor bump carried by a
single feat (read_process_memory_into, #72).

Not major: PyMemoryEditor.__all__ is untouched, compile_pattern is
byte-for-byte identical to before (verified differentially against the previous
implementation), and the cheat table's JSON round-trips on every value type, so
saved tables keep loading.

Checklist (complete all items):

• Added tests as necessary.
• There is no breaking change for existing features.

References:

Closes nothing; follows #87 and #88.

Notes:

One line changes — pyproject.toml declares dynamic = ["version"] and
[tool.hatch.version] reads it from PyMemoryEditor/__init__.py, so that is
the only place the number lives. Confirmed by building the wheel:
pymemoryeditor-2.2.0-py3-none-any.whl.

Suite is green at 562 passed / 13 skipped and make lint is clean.