Update README.md and 1.2.9

[ZLI-afk]

Upgrade to 1.2.9 and update README.md

[codecov]

Codecov Report

Attention: Patch coverage is 34.84848% with 43 lines in your changes missing coverage. Please review.

Project coverage is 59.34%. Comparing base (8128758) to head (f50dad2).
Report is 31 commits behind head on devel-1.2.0.

Files with missing lines	Patch %	Lines
apex/core/calculator/lib/lammps_utils.py	15.38%	11 Missing ⚠️
apex/core/property/Phonon.py	23.07%	10 Missing ⚠️
apex/core/calculator/Lammps.py	33.33%	8 Missing ⚠️
apex/core/calculator/lib/abacus_utils.py	25.00%	6 Missing ⚠️
apex/core/calculator/VASP.py	20.00%	4 Missing ⚠️
apex/core/calculator/ABACUS.py	0.00%	3 Missing ⚠️
apex/core/property/Gamma.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           devel-1.2.0      #82      +/-   ##
===============================================
- Coverage        59.52%   59.34%   -0.19%     
===============================================
  Files               55       56       +1     
  Lines             6322     6343      +21     
===============================================
+ Hits              3763     3764       +1     
- Misses            2559     2579      +20     

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