Drop Python 3.8 support #1592

Job	Run time
Build Dash Package	3m 3s
Build on Windows	5m 9s
Detect Relevant Path Changes	5s
Lint & Unit Tests (Python 3.9)	3m 0s
Typing Tests	3m 51s
Lint & Unit Tests (Python 3.12)	3m 6s
Main Dash Tests (Python 3.12, Group 2)	10m 11s
Main Dash Tests (Python 3.9, Group 3)	6m 55s
Main Dash Tests (Python 3.9, Group 1)	7m 7s
Main Dash Tests (Python 3.12, Group 1)	8m 22s
Main Dash Tests (Python 3.12, Group 3)	8m 1s
Main Dash Tests (Python 3.9, Group 2)	9m 4s
Run Backend Callback Tests (Python ${{ matrix.python-version }})	-1s
HTML Components Tests (Python ${{ matrix.python-version }})	-1s
Table Server Tests (Group ${{ matrix.test-group }})	-1s
DCC Integration Tests (Python ${{ matrix.python-version }}, Group ${{ matrix.test-group }})	-1s
Run Background & Async Callback Tests (Python ${{ matrix.python-version }})	-1s
DCC Lint Tests (Python ${{ matrix.python-version }})	-1s
Table Unit/Lint Tests (Python ${{ matrix.python-version }})	-1s
Dash Table Visual Tests	-1s
WebSocket Tests (Python ${{ matrix.python-version }})	-1s
Consolidated Test Report	10s
Finalize Percy Snapshots	20s
Store Build Artifacts	0s
	1h 8m 15s

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