line = 'xxx出生于2001年6月'
line1 = 'xxx出生于2001/6/1'
line2 = 'xxx出生于2001-6-1'
line3 = 'xxx出生于2001-06-01'
line4 = 'xxx出生于2001-06'
import re
# 最后或方法用小括号（可有可无）
pattern = '.*出生于(d{4}[年/-]d{1,2}([月/-]$|$|[月/-]d{1,2}))'
result = re.match(pattern, line4)
print(result.group(1))
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