This changeset updates the test environment to all stable dependencies.

Builds on top of #545, #524 and the PRs linked there:

• Report any unhandled promise rejections promise#248 and [3.x] Add PHPStan to test environment with max level promise#246
• [4.x] Update test suite to avoid unhandled promise rejections async#79 and [3.x] Update test suite to avoid unhandled promise rejections async#80
• Update test suite to avoid unhandled promise rejections dns#215
• Update unwrapped stream to avoid unhandled promise rejections promise-stream#37
• Update test suite to avoid unhandled promise rejections promise-timer#66
• Update test suite to avoid unhandled promise rejections socket#307
• Update test suite to avoid unhandled promise rejections http#501
• Update test suite to collect all garbage cycles socket#308
• Update test suite to collect all garbage cycles promise-stream#38