bootstrap: gpg: feat: Add macOS support

.config/yadm/bootstrap.d/gpg.sh

@@ -1,7 +1,39 @@
 if ! command -v gpg &> /dev/null; then
     echo 'Installing gpg'
+
+    source $HOME/.zshenv
+
+    if [[ "$OSNAME" == "Linux" ]]; then
+        # Linux
+        if [[ "$DISTRO_TYPE" == "debian" ]]; then
+            # Debian-based
             sudo apt update
             sudo apt install gpg -y
+        elif [[ "$DISTRO_TYPE" == "rpm" ]]; then
+            # RPM-based
+            echo 'ERROR: Currently unsupported'
+            echo 'Exiting...'
+            exit 1
+        elif [[ "$DISTRO_TYPE" == "arch" ]]; then
+            # Arch-based
+            echo 'ERROR: Currently unsupported'
+            echo 'Exiting...'
+            exit 1
+        else
+            # Unknown distro
+            echo 'ERROR: Unknown distro'
+            echo 'Exiting...'
+            exit 1
+        fi
+    elif [[ "$OSNAME" == "macOS" ]]; then
+        # macOS
+        brew install gpg
+    else
+        # Unknown
+        echo 'ERROR: Unknown OS'
+        echo 'Exiting...'
+        exit 1
+    fi
 fi
 
 echo 'gpg is installed'