use Lua script to pop the task atomically

[michalsn]

Description
This PR ensures that tasks in Redis are taken off the queue atomically.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[coveralls]

Pull Request Test Coverage Report for Build 12828039111

Details

• 38 of 40 (95.0%) changed or added relevant lines in 5 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 90.508%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/Handlers/PredisHandler.php	14	15	93.33%
src/Handlers/RedisHandler.php	14	15	93.33%

Files with Coverage Reduction	New Missed Lines	%
src/Handlers/RedisHandler.php	1	89.86%

Totals
Change from base Build 12647486320:	-0.1%
Covered Lines:	534
Relevant Lines:	590

---

💛 - Coveralls

[paulbalandan]

I'm not familiar with Lua so I'll trust you on this. 👍🏻

[michalsn]

Thank you @paulbalandan and @samsonasik