Debug devkitPro install: print installer script before running

Print the installer script contents in CI log so we can see what URLs
it tries to fetch. Also add /etc/mtab symlink as the devkitPro base
Docker image does.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/actions/setup-devkitpro/action.yml

@@ -21,15 +21,14 @@ runs:
     - name: Install devkitPro pacman
       shell: bash
       run: |
-        wget -q https://apt.devkitpro.org/devkitpro-pacman.asc \
-          -O /tmp/devkitpro-pacman.asc
-        sudo mkdir -p /usr/share/keyrings
-        sudo mv /tmp/devkitpro-pacman.asc /usr/share/keyrings/devkitpro-pub.gpg
-        echo "deb [signed-by=/usr/share/keyrings/devkitpro-pub.gpg] https://apt.devkitpro.org stable main" \
-          | sudo tee /etc/apt/sources.list.d/devkitpro.list
-        sudo apt-get update
-        sudo apt-get install -y devkitpro-pacman
-        sudo dkp-pacman -Sy
+        sudo ln -sf /proc/self/mounts /etc/mtab
+        wget https://apt.devkitpro.org/install-devkitpro-pacman \
+          -O /tmp/install-devkitpro-pacman
+        echo "=== installer script contents ==="
+        cat /tmp/install-devkitpro-pacman
+        echo "================================="
+        chmod +x /tmp/install-devkitpro-pacman
+        sudo /tmp/install-devkitpro-pacman
         echo "DEVKITPRO=/opt/devkitpro" >> $GITHUB_ENV
         echo "DEVKITPPC=/opt/devkitpro/devkitPPC" >> $GITHUB_ENV
         echo "/opt/devkitpro/tools/bin" >> $GITHUB_PATH