fix(pihole): support special characters in pihole password

[alex-ac]

What does it do ?

Current implementation does not handle special characters in pihole password correctly. It skips proper JSON marshalling of the request & sends invalid json to pihole API. This change fixes it by introducing proper JSON marshalling.

Motivation

I've hit this problem myself on my homelab setup, here's a log:

time="2025-12-02T13:20:36Z" level=debug msg="Fetching new token from http://http.pi-hole.svc.cluster.local/api/auth"
time="2025-12-02T13:20:36Z" level=debug msg="Error on request http://http.pi-hole.svc.cluster.local/api/auth"
time="2025-12-02T13:20:36Z" level=debug msg="Body of the request {}"
time="2025-12-02T13:20:36Z" level=fatal msg="received 400 status code from request: [bad_request] Invalid request body data (no valid JSON), error at hint (\\hei0MachahmaeThoo7u\"}) - 0.000226s"

Hint in the log is part of the request json starting with invalid escape sequence \h which happened because my password contains backslash.

More

• [x] Yes, this PR title follows Conventional Commits
• [x] Yes, I added unit tests
• [x] Yes, I updated end user documentation accordingly

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• :white_check_mark: login: alex-ac / name: Aleksandr Derbenev (4670796baf5afe4694877d8a5d8ad5f4b6bdfa64, 9481752786637ba8c610c733a799ac8ee75a4c60)

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[k8s-ci-robot]

Hi @alex-ac. Thanks for your PR.

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[mloiseleur]

/ok-to-test

[coveralls]

Pull Request Test Coverage Report for Build 19861145459

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 20 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.008%) to 78.676%

---

Files with Coverage Reduction	New Missed Lines	%
openshift_route.go	1	79.49%
pihole/clientV6.go	19	92.26%
<!--	Total:	20

Totals
Change from base Build 19855624490:	-0.008%
Covered Lines:	16013
Relevant Lines:	20353

---

💛 - Coveralls