fix: update vulnerable dependencies and drop Python 3.9 (EOL)

[b-per]

Summary

Resolves all 22 open Dependabot security alerts by updating vulnerable dependencies. Also drops Python 3.9 (EOL since October 2025) since requests>=2.33.0 requires Python>=3.10.

Package	Before	After	Severity
requests	2.32.5	2.33.1	medium
deepdiff	8.6.1	8.6.2	critical/high
jinja2	constraint tightened to >=3.1.6	(already at 3.1.6)	medium
pytest	7.4.4	9.0.3	medium
pygments	2.18.0	2.20.0	low
markdown	3.7	3.10.2	medium
pymdown-extensions	10.14.3	10.21.2	low
filelock	3.19.1	3.29.0	medium
urllib3	2.6.3	2.6.3	(already safe)

Note: urllib3 and jinja2 were already at safe versions in the lockfile — only their pyproject.toml constraints were too loose.

Breaking change

Drops Python 3.9 support — EOL since October 2025, and requests>=2.33.0 requires Python>=3.10. The CI matrix is updated accordingly.

Test plan

• All 171 tests pass locally with uv run pytest
• CI passes on Python 3.10–3.14

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
src/dbt_jobs_as_code
main.py	310	160	48%	120–123, 129, 168–169, 200–203, 209, 245–329, 400–405, 418–419, 437–438, 442–444, 461–510, 539–597, 628–673, 678–679, 683
src/dbt_jobs_as_code/client
__init__.py	179	46	74%	16, 53–54, 62, 99–100, 119–120, 139–140, 155–156, 170–171, 187–188, 205, 215, 295–310, 333, 349–350, 360–372, 375–386, 391–400
src/dbt_jobs_as_code/cloud_yaml_mapping
change_set.py	235	30	87%	27–29, 59, 65–66, 155, 212, 224, 247, 251–252, 258–260, 275–278, 334–348, 401–423, 459–473
src/dbt_jobs_as_code/importer
__init__.py	27	7	74%	14–15, 22–27
src/dbt_jobs_as_code/schemas
__init__.py	23	2	91%	68, 78
common_types.py	60	3	95%	67–68, 91
config.py	14	1	93%	18
job.py	133	7	95%	237, 242, 258–268
TOTAL	1184	256	78%

Tests	Skipped	Failures	Errors	Time
171	0 💤	0 ❌	0 🔥	15.640s ⏱️