workflow/tests: Remove redundant style check

The reason the redundant check exists is that we used to have separate core taps for MacOS and Linux but they have been merged. It also means that we don't have to manually fetch `homebrew/core` anymore.

.github/workflows/tests.yml

@@ -80,7 +80,7 @@ jobs:
       - name: Run brew readall on all taps
         run: brew readall --eval-all --aliases
 
-      - name: Run brew style on homebrew-core for Linux
+      - name: Run brew style on homebrew-core
         run: brew style --display-cop-names homebrew/core
 
       - name: Run brew audit --skip-style on all taps
@@ -88,12 +88,6 @@ jobs:
 
       - name: Set up all Homebrew taps
         run: |
-          HOMEBREW_REPOSITORY="$(brew --repo)"
-          HOMEBREW_CORE_REPOSITORY="${HOMEBREW_REPOSITORY}/Library/Taps/homebrew/homebrew-core"
-          git -C "${HOMEBREW_CORE_REPOSITORY}" remote add homebrew_core https://github.com/Homebrew/homebrew-core
-          git -C "${HOMEBREW_CORE_REPOSITORY}" fetch homebrew_core || git -C "${HOMEBREW_CORE_REPOSITORY}" fetch homebrew_core
-          git -C "${HOMEBREW_CORE_REPOSITORY}" checkout --force -B master homebrew_core/master
-
           brew tap homebrew/aliases
           brew tap homebrew/autoupdate
           brew tap homebrew/bundle
@@ -109,12 +103,7 @@ jobs:
           brew update-reset Library/Taps/homebrew/homebrew-bundle
 
           # brew style doesn't like world writable directories
-          sudo chmod -R g-w,o-w "${HOMEBREW_REPOSITORY}/Library/Taps"
-
-      - name: Run brew style on homebrew-core for macOS
-        run: brew style --display-cop-names homebrew/core
-        env:
-          HOMEBREW_SIMULATE_MACOS_ON_LINUX: 1
+          sudo chmod -R g-w,o-w "$(brew --repo)/Library/Taps"
 
       - name: Run brew audit --skip-style on homebrew-core for macOS
         run: brew audit --skip-style --except=version --tap=homebrew/core