Chore: apparently llvm script doesnt support 7

Author: RDambrosio016

.github/workflows/rust.yml

@@ -51,9 +51,7 @@ jobs:
       - name: Install LLVM 7.1.0
         if: contains(matrix.os, 'ubuntu')
         run: | 
-            wget https://apt.llvm.org/llvm.sh
-            chmod +x llvm.sh
-            sudo ./llvm.sh 7.1.0
+            sudo apt-get install llvm-7-dev
 
       - name: Load Rust Cache
         uses: Swatinem/rust-cache@v1