Remove unused lintian overrides (#1931)

I noticed that lintian reports 3 unused overrides, see e.g. [the “Run
lintian” step of this CI
build](https://app.circleci.com/pipelines/github/tiny-pilot/tinypilot/4891/workflows/2b7f55b2-d2f8-4085-ac30-6a4676ecb083/jobs/37639):

```
N: 21 hints overridden (21 warnings); 3 unused overrides
```

I haven’t investigated this, but I assume the issues just went away at
some point when we upgraded the offending packages.

With this PR, [the unused overrides go back to
`0`](https://app.circleci.com/pipelines/github/tiny-pilot/tinypilot/4897/workflows/3d482ece-5100-4ee6-934f-b82184386438/jobs/37701):

```
N: 21 hints overridden (21 warnings); 0 unused overrides
```

This PR is succeeds
tiny-pilot/tinypilot-pro#1719.
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Co-authored-by: Jan Heuermann <jan@jotaen.net>

Author: jotaen4tinypilot

debian-pkg/debian/tinypilot.lintian-overrides

@@ -1,10 +1,7 @@
 # Suppress complaints about third-party dependencies we don't control.
-tinypilot: embedded-javascript-library opt/tinypilot/venv/lib/python*/site-packages/werkzeug/debug/shared/jquery.js please use libjs-jquery
 tinypilot: script-not-executable [opt/tinypilot/venv/lib/python*/site-packages/greenlet/tests/test_version.py]
 tinypilot: script-not-executable [opt/tinypilot/venv/lib/python*/site-packages/pkg_resources/_vendor/appdirs.py]
 tinypilot: script-not-executable [opt/tinypilot/venv/lib/python*/site-packages/setuptools/command/easy_install.py]
-tinypilot: embedded-library libyaml opt/tinypilot/venv/lib/python*/site-packages/yaml/*.so
-tinypilot: hardening-no-relro [opt/tinypilot/venv/lib/python*/site-packages/yaml/*.so]
 tinypilot: national-encoding opt/tinypilot/venv/lib/python*/site-packages/passlib/tests/sample1c.cfg
 
 # Lintian doesn't recognize the Python interpreter when it's within the