You should slow down and remain behind the bicyclist.
Trying to overtake him/her is very dangerous because it could cause an accident and hurt the cyclist. This is because the slighest car movement next to the bicycle, changes the air flow and can cause the cyslist to lose his/her balance and fall. So, even if overtaking was allowed on this narrow road, the safest choice would be to remain behind the bicyclist and keep a safe distance from him/her.