Download Source
wget https://ftp.postgresql.org/pub/source/v12.8/postgresql-12.8.tar.bz2
Extract
tar -xvjf postgresql-12.8.tar.bz2
Go to
cd postgresql-12.8/
Install Dependencies
sudo apt-get install build-essential -y
sudo apt-get install libreadline-dev -y
sudo apt-get install zlib1g-dev -y
Configure
./configure --prefix=~/postgresql-12
Make & Make Install
make -j4 && make install