Reduce dependabot PR frequency to weekly

[echoix]

Reduce the frequency of dependabot updates during the transition period with renovate. Renovate seems to handle more deps, but just in case dependabot handled another case, I'm still keeping it active. But we don't need duplicate PRs for everything.

Proposed Changes

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Readiness Checklist

Author/Contributor

• [ ] Add entry to the CHANGELOG listing the change and linking to the corresponding issue (if appropriate)
• [ ] If documentation is needed for this change, has that been included in this pull request

Reviewing Maintainer

• [ ] Label as breaking if this is a large fundamental change
• [ ] Label as either automation, bug, documentation, enhancement, infrastructure, or performance

[github-actions[bot]]

🦙 MegaLinter status: ⚠️ WARNING

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ API	spectral	2		0	3.16s
✅ BASH	bash-exec	5		0	0.03s
✅ BASH	shellcheck	5		0	0.13s
✅ BASH	shfmt	5	0	0	0.66s
✅ COPYPASTE	jscpd	yes		no	4.32s
✅ DOCKERFILE	hadolint	130		0	18.51s
✅ JSON	jsonlint	18		0	0.25s
✅ JSON	v8r	20		0	31.22s
⚠️ MARKDOWN	markdownlint	265	0	272	42.8s
✅ MARKDOWN	markdown-table-formatter	265	0	0	141.11s
✅ OPENAPI	spectral	2		0	3.21s
⚠️ PYTHON	bandit	211		64	3.92s
✅ PYTHON	black	211	0	0	6.32s
✅ PYTHON	flake8	211		0	2.99s
✅ PYTHON	isort	211	0	0	1.93s
✅ PYTHON	mypy	211		0	21.04s
✅ PYTHON	pylint	211		0	17.35s
✅ PYTHON	ruff	211	0	0	0.85s
✅ REPOSITORY	checkov	yes		no	42.4s
✅ REPOSITORY	git_diff	yes		no	0.64s
⚠️ REPOSITORY	grype	yes		1	25.04s
✅ REPOSITORY	secretlint	yes		no	19.58s
✅ REPOSITORY	trivy	yes		no	20.79s
✅ REPOSITORY	trivy-sbom	yes		no	4.74s
⚠️ REPOSITORY	trufflehog	yes		1	13.13s
✅ SPELL	cspell	693		0	30.88s
⚠️ SPELL	lychee	346		2	6.65s
✅ XML	xmllint	3	0	0	0.62s
✅ YAML	prettier	161	0	0	6.43s
✅ YAML	v8r	102		0	196.25s
✅ YAML	yamllint	162		0	2.41s

See detailed report in MegaLinter reports

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