[ruby/psych] Eagerly require `date`. #610

Job	Run time
make (check, cppflags=-DVM_CHECK_MODE)	8m 29s
make (check, i686)	10m 17s
make (check, --disable-yjit)	6m 34s
make (check, --enable-shared --enable-load-relative)	7m 4s
make (check, true, --with-shared-gc=/home/runner/ruby_gc)	7m 19s
make (test-bundler-parallel, 50)	28m 16s
make (test-bundled-gems)	16m 45s
make (check, ubuntu-20.04)	9m 23s
make (check, ubuntu-24.04)	9m 31s
Ubuntu result	1s
	1h 43m 39s

Provide feedback