build: upgrade base image & MongoDB; drop py3.8 #313

Job	Run time
Run linting and unit tests (3.9, 3.9-slim-bookworm, 4.4, 12345)	3m 29s
Run linting and unit tests (3.9, 3.9-slim-bookworm, 5.0, 12345)	3m 33s
Run linting and unit tests (3.9, 3.9-slim-bookworm, 6.0, 12345)	3m 30s
Run linting and unit tests (3.9, 3.9-slim-bookworm, 7.0, 12345)	3m 23s
Run linting and unit tests (3.10, 3.10-slim-bookworm, 4.4, 12345)	3m 25s
Run linting and unit tests (3.10, 3.10-slim-bookworm, 5.0, 12345)	3m 22s
Run linting and unit tests (3.10, 3.10-slim-bookworm, 6.0, 12345)	3m 22s
Run linting and unit tests (3.10, 3.10-slim-bookworm, 7.0, 12345)	3m 12s
Run linting and unit tests (3.11, 3.11-slim-bookworm, 4.4, 12345)	3m 25s
Run linting and unit tests (3.11, 3.11-slim-bookworm, 5.0, 12345)	3m 28s
Run linting and unit tests (3.11, 3.11-slim-bookworm, 6.0, 12345)	3m 17s
Run linting and unit tests (3.11, 3.11-slim-bookworm, 7.0, 12345)	3m 19s
Docker (3.9, 3.9-slim-bookworm)	1m 24s
Docker (3.10, 3.10-slim-bookworm)	1m 25s
Docker (3.11, 3.11-slim-bookworm, latest)	1m 22s
	44m 56s

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