Fix fetch mirror errors

Author: AnkitBarik

.github/workflows/main.yml

@@ -32,6 +32,7 @@ jobs:
       # Runs a set of commands using the runners shell
       - name: Install pre-requisites
         run: |
+          sudo apt-get update
           sudo apt-get -y install gfortran gcc g++ cmake liblapack-dev libgomp1
           sudo apt-get -y install mpich libmpich-dev
           sudo apt-get -y install python3-gi python3-gi-cairo gir1.2-gtk-3.0