test: cover override+public+constant in naming-convention regression

[js360000]

Summary

Adds an explicit regression fixture for the scenario described in #930: a public constant that overrides an interface getter must not be flagged by the naming-convention detector's UPPER_CASE_WITH_UNDERSCORES rule.

The behavior has been correct since the public-constant skip was added in slither/detectors/naming_convention/naming_convention.py — but the existing no_warning_for_public_constants.sol fixture only exercises a plain public constant. This change locks in the override variant so a future refactor of the public/override ordering can't silently regress.

Why this instead of code changes

I verified against the current detector code that the issue's repro:

interface I {
    function version() external view returns (uint256);
}
contract C is I {
    uint256 public constant override version = 1;
}

…already produces zero findings because the detector skips the entire public branch before ever evaluating override. @cats2101 came to the same conclusion in the 2026-03-31 issue comment, but the case still isn't pinned by a fixture. Adding the regression test now means anyone touching naming_convention.py later will get an immediate signal if the ordering of the public skip vs. the is_constant branch gets swapped.

What changed

• tests/e2e/detectors/test_data/naming-convention/0.6.11/no_warning_for_public_constants_with_override.sol — new fixture exercising override+public+constant on solc 0.6.11.
• tests/e2e/detectors/test_data/naming-convention/0.7.6/no_warning_for_public_constants_with_override.sol — same for solc 0.7.6.
• Matching empty snapshots in tests/e2e/detectors/snapshots/ (matches the existing no_warning_for_public_constants.sol baselines, which are also empty).
• Two new Test(NamingConvention, …) entries in tests/e2e/detectors/test_detectors.py.

Pre-0.6 solc versions are intentionally skipped — the override keyword is a 0.6.x addition.

Diff

```
.../naming-convention/0.6.11/no_warning_for_public_constants_with_override.sol | 14 ++++++++++++++
.../naming-convention/0.7.6/no_warning_for_public_constants_with_override.sol | 14 ++++++++++++++
tests/e2e/detectors/snapshots/..._0_6_11..._with_override_sol__0.txt | 0
tests/e2e/detectors/snapshots/..._0_7_6..._with_override_sol__0.txt | 0
tests/e2e/detectors/test_detectors.py | 10 ++++++++++
5 files changed, 38 insertions(+)
```

Closes

Closes #930.

[CLAassistant]

All committers have signed the CLA.