fix: Prevent `query->equalTo` from overriding other conditions

[dplewis]

New Pull Request Checklist

• [ ] I am not disclosing a vulnerability.
• [ ] I am creating this PR in reference to an issue.

Issue Description

Closes: https://github.com/parse-community/parse-php-sdk/issues/476, https://github.com/parse-community/parse-php-sdk/pull/477

Approach

TODOs before merging

• [x] Add tests

[parse-github-assistant[bot]]

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[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (0570f15) 98.62% compared to head (72a3246) 98.62%.

:exclamation: Current head 72a3246 differs from pull request most recent head 61403e0. Consider uploading reports for the commit 61403e0 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #510 +/- ## ========================================= Coverage 98.62% 98.62% Complexity 1072 1072 ========================================= Files 38 38 Lines 3264 3264 ========================================= Hits 3219 3219 Misses 45 45 ``` | [Impacted Files](https://app.codecov.io/gh/parse-community/parse-php-sdk/pull/510?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=parse-community) | Coverage Δ | | |---|---|---| | [src/Parse/ParseQuery.php](https://app.codecov.io/gh/parse-community/parse-php-sdk/pull/510?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=parse-community#diff-c3JjL1BhcnNlL1BhcnNlUXVlcnkucGhw) | `99.76% <100.00%> (ø)` | |

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[parseplatformorg]

🎉 This change has been released in version 2.3.1