Beef installation 'libgcc-9-dev' not available. What do i do about it?

Note, selecting 'libreadline-dev' instead of 'libreadline6-dev' Package libgcc-9-dev is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source

E: Package 'libgcc-9-dev' has no installation candidate

Error:- package has no installation candidate

1. TYPE IN TERMINAL (nano /etc/apt/sources.list) DELETE ALL LINES INTO IT

2. GO TO (https://www.kali.org/docs/general-use/kali-linux-sources-list-repositories/)

   or

3. copy repositories below mentioned
   COPY AND PASTE THESE LINES INTO SOURCE LIST

   {*deb http://http.kali.org/kali kali-rolling main non-free contrib*
   
   *deb http://http.kali.org/kali kali-last-snapshot main non-free contrib*
   
   *deb http://http.kali.org/kali kali-experimental main non-free contrib*
   
   *deb-src http://http.kali.org/kali kali-rolling main non-free contrib*} 
   

4. TO EXIT AND SAVE press (ctrl+x) and press Y to confirm saving

5. Type apt update && apt upgrade in terminal

//hope it will work//