Refactor GitHub workflows and prepare release 0.12.0 #513

Job	Run time
Run Slow or Expensive Tests (e.g. SaaS)?	1s
Tests (Python-3.8)	6m 43s
Tests (Python-3.9)	6m 57s
Tests (Python-3.10)	6m 48s
Checks / Version Check & Build Documentation	49s
Checks / Linting and Type checks (Python-3.8)	1m 7s
Checks / Linting and Type checks (Python-3.9)	1m 14s
Checks / Linting and Type checks (Python-3.10)	1m 8s
Checks / Linting and Type checks (Python-3.11)	1m 9s
Gate 1 - Regular CI	1s
metrics / Generate Status Report	46s
Run Slow or Expensive Tests (e.g. SaaS) if Requested	0s
Gate 2 - Allow Merge	0s
	26m 43s

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