2.x php8 compat

[alex-dna]

Hi.
We found that using the module with PHP 8 triggered a few deprecation warnings, so this MR aims at correcting them.
This is also bumping the minimum PHP version to 7.1. Not sure if that something you would want to do.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.54%. Comparing base (70d9b95) to head (a3609c0).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #250      +/-   ##
============================================
+ Coverage     83.51%   84.54%   +1.03%     
  Complexity      208      208              
============================================
  Files            10       10              
  Lines           558      550       -8     
============================================
- Hits            466      465       -1     
+ Misses           92       85       -7     

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[aik099]

I agree with your proposal. Let's do a few more changes to prepare PR for merging.

Please also add a line in the CHANGELOG.md file (1st line with a change + 2nd line at the file bottom for PR author link to work if you're a 1st time contributor in this repository).

[aik099]

Almost there.

[aik099]

Almost there. Everything else looks solid.

[aik099]

Merging. Thank you @alex-dna.

If you have time to spend on this project, that I'll be happy to review your PRs.