chore: update shell configuration and font package

- add default configuration for shell
- change font package from `font-hack-nerd-font` to `font-fira-code-nerd-font`

.github/workflows/ci.yml

@@ -5,6 +5,10 @@ on:
     branches:
       - ci
 
+defaults:
+  run:
+    shell: bash # necessary for windows
+
 jobs:
   fmt:
     name: cargo fmt
@@ -86,7 +90,7 @@ jobs:
         run: |
           if [[ $RUNNER_OS == "macOS" ]]; then
             curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh && brew upgrade
-            brew install font-hack-nerd-font
+            brew install --cask font-fira-code-nerd-font
           fi
 
       - name: cargo test