Use OS and architecture when fetching configlet.

bin/fetch-configlet

@@ -2,7 +2,29 @@
 
 LATEST=https://github.com/exercism/configlet/releases/latest
 
+OS=$(
+case $(uname) in
+    Darwin*)
+        echo "mac";;
+    Linux*)
+        echo "linux";;
+    Windows*)
+        echo "windows";;
+    *)
+        echo "linux";;
+esac)
+
+ARCH=$(
+case $(uname -m) in
+    *64*)
+        echo 64bit;;
+    *32*)
+        echo 32bit;;
+    *)
+        echo 64bit;;
+esac)
+
 VERSION="$(curl --head --silent $LATEST | awk -v FS=/ '/Location:/{print $NF}' | tr -d '\r')"
-URL=https://github.com/exercism/configlet/releases/download/$VERSION/configlet-linux-64bit.tgz
+URL=https://github.com/exercism/configlet/releases/download/$VERSION/configlet-$OS-${ARCH}.tgz
 
 curl -s --location $URL | tar xz -C bin/