docs: remove mention of py38 compatibility from readme (#35001) #159

Job	Run time
collect-and-verify	4m 45s
lms-1(py=3.11,dj=pinned,mongo=7.0)	13m 37s
lms-2(py=3.11,dj=pinned,mongo=7.0)	13m 18s
lms-3(py=3.11,dj=pinned,mongo=7.0)	19m 38s
lms-4(py=3.11,dj=pinned,mongo=7.0)	24m 29s
lms-5(py=3.11,dj=pinned,mongo=7.0)	13m 34s
lms-6(py=3.11,dj=pinned,mongo=7.0)	18m 54s
openedx-1-with-lms(py=3.11,dj=pinned,mongo=7.0)	15m 46s
openedx-2-with-lms(py=3.11,dj=pinned,mongo=7.0)	18m 13s
openedx-1-with-cms(py=3.11,dj=pinned,mongo=7.0)	11m 13s
openedx-2-with-cms(py=3.11,dj=pinned,mongo=7.0)	7m 31s
cms-1(py=3.11,dj=pinned,mongo=7.0)	5m 18s
cms-2(py=3.11,dj=pinned,mongo=7.0)	19m 6s
common-with-lms(py=3.11,dj=pinned,mongo=7.0)	11m 46s
common-with-cms(py=3.11,dj=pinned,mongo=7.0)	7m 2s
xmodule-with-lms(py=3.11,dj=pinned,mongo=7.0)	7m 41s
xmodule-with-cms(py=3.11,dj=pinned,mongo=7.0)	7m 56s
compile-warnings-report	6s
Unit tests successful	2s
coverage	0s
	3h 39m 55s

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