Remove comments that imply Bootstrap 4 is still supported in BL9 (it … #531

Job	Run time
lint / lint	51s
docker_build / build	30s
test / set_matrix	3s
test / ruby 3.4 \| rails 8.0.3 ViewComponent 3	4m 13s
test / ruby 3.4 \| rails 7.1.5.1	4m 35s
test / ruby 3.4 \| rails 8.1.0	3m 57s
test / ruby 3.4 \| rails 8.1.0 \| esbuild	4m 29s
test / ruby 3.4 \| rails 7.2.2.1	3m 59s
test / ruby 3.3 \| rails 7.1.5.1 \| API	2m 43s
test / ruby 3.2 \| rails 7.1.5.1 \| Solr 8.11.2	4m 15s
test / ruby 3.3 \| rails 8.0.3 \| esbuild	4m 34s
test / ruby 3.3 \| rails 8.0.3	4m 35s
test / ruby 3.3 \| rails 7.1.5.1 \| Propshaft	4m 36s
test / ruby 3.3 \| rails 7.2.2.1 \| Propshaft, esbuild	4m 52s
	48m 12s

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