Add `dbt-core~=1.8.0a1` as convenience dep #5161

Job	Run time
unit test / python 3.8	21m 39s
build packages	17s
unit test / python 3.9	20m 16s
code-quality	1m 10s
unit test / python 3.10	56s
unit test / python 3.11	1m 1s
verify packages / python 3.8 / ubuntu-latest	46s
verify packages / python 3.9 / ubuntu-latest	53s
verify packages / python 3.10 / ubuntu-latest	54s
verify packages / python 3.11 / ubuntu-latest	44s
verify packages / python 3.8 / macos-latest	1m 15s
verify packages / python 3.9 / macos-latest	1m 0s
verify packages / python 3.10 / macos-latest	1m 11s
verify packages / python 3.11 / macos-latest	1m 29s
verify packages / python 3.8 / windows-latest	1m 47s
verify packages / python 3.9 / windows-latest	1m 57s
verify packages / python 3.10 / windows-latest	2m 10s
verify packages / python 3.11 / windows-latest	2m 30s
	1h 1m 55s

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