Invalid conversion to uBO syntax - unpaired off `'` must be escaped in `:contains()`

[Alex-302]

Parity checking and shielding of unpaired odd characters is required

• error - unpaired

example.com#?#main:has(> div:contains(te'st))
example.com#?#main:has(> div:contains(t'e's't))

• ok, paired

example.com#?#main:has(> div:contains(t'es't))

• ok, paired, unpaired - ecsaped

example.com#?#main:has(> div:contains(t'e's\'t))