Advertise supported Python versions via trove classifiers

requires-python stays ">=3.10" (already correct and matching the CI matrix
of 3.10-3.14); add the per-version Programming Language :: Python :: 3.10-3.14
classifiers and "3 :: Only" so the PyPI page lists supported versions.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,7 @@
 - **Invalid reports now explain *why* they are invalid.** The parser still catches broadly so one malformed report can never crash a batch, but the diagnostics are no longer a bare `Not a valid report`. `parse_report_file()` keeps each format parser's specific error as it tries aggregate XML → SMTP TLS JSON → report email, and when all three reject the input it sniffs the content shape to surface the single relevant reason — e.g. `Invalid aggregate report: Missing field: 'org_name'`, `Invalid SMTP TLS report: Missing required field: date-range`, or `Not a recognized report format (not a DMARC aggregate XML report, an SMTP TLS JSON report, or a DMARC report email)`. This is the message the CLI already logs (`Failed to parse <file> - <reason>`), so operators see the cause without a code change on their end.
 - **Original exceptions are now chained.** Every parser catch site re-raises with `raise … from <original>`, so the underlying `ExpatError`, `json.JSONDecodeError`, `KeyError`, and archive/decompression errors are preserved on `__cause__` for library callers and tracebacks instead of being flattened into a string. Behavior is otherwise unchanged — the same exception *types* are still raised.
 - **Unexpected errors cite their origin in debug mode.** When a catch-all branch turns an unforeseen exception into a generic `Unexpected error: …` / archive / mail-parse failure, the message now appends `(raised at <file>:<line>)` pinpointing the deepest traceback frame — but only when the `parsedmarc` logger is at `DEBUG` level (e.g. the CLI's `--debug`). Normal-level output is unchanged.
+- Added per-version `Programming Language :: Python :: 3.10`–`3.14` (and `3 :: Only`) trove classifiers so the PyPI page advertises the supported Python versions. No change to `requires-python` (`>=3.10`).
 
 ### Bug fixes
 

pyproject.toml

@@ -27,7 +27,13 @@ classifiers = [
     "Intended Audience :: Information Technology",
     "License :: OSI Approved :: Apache Software License",
     "Operating System :: OS Independent",
-    "Programming Language :: Python :: 3"
+    "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3 :: Only",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
 ]
 requires-python = ">=3.10"
 dependencies = [