Don't write `/usr/bin/python3` into code

[BailPlus]

In some circumstances, the path of python executable file isn't the fixed one. For example, it's in /data/data/com.termux/files/usr/bin/python. It results in playsound throws error on termux. For another example, one who compiles python by self can install it anywhere he/she wants. Instead, you could use sys.executable to automatically detect it.

[Dragon1573]

This might not only affect Termux, but also other Android device without root privileges.

For App coding.yu.pythoncompiler.new created by @yuruxuan, the interpreter is installed as /data/user/0/coding.yu.pythoncompiler.new/files/PYROOT3/bin/python3.