import re

pattern = r"^(\*\s+\w+:\s)(.*(?:\n(?!\*\s+\w+:\s).*)*)"

s = ("* Major: This is a **Major** change\n"
	"* Minnor: This is is a minor change with a typo\n"
	"* Patch: This\n"
	"is a multiline\n"
	"  patch")

result = re.findall(pattern, s, re.MULTILINE)
print(result)