update-deps: Fix DiffHighlight's URL and refactor

Fetch `DiffHighlight.pm` instead of `diff-highlight`

Author: oranja

update-deps.sh

@@ -1,4 +1,11 @@
 #!/bin/bash
 
-curl -Lo "third_party/diff-highlight/diff-highlight" "https://github.com/git/git/raw/master/contrib/diff-highlight/diff-highlight"
-curl -Lo "third_party/diff-highlight/README" "https://github.com/git/git/raw/master/contrib/diff-highlight/README"
+DIFFHIGHLIGHT_RAW_URL_BASE="https://raw.githubusercontent.com/git/git/master/contrib/diff-highlight"
+DIFFHIGHLIGHT_FILES=( "DiffHighlight.pm" "README" )
+
+for file in "${DIFFHIGHLIGHT_FILES[@]}";
+do
+  url="$DIFFHIGHLIGHT_RAW_URL_BASE/$file"
+  echo "$url"
+  curl -#Lo "lib/$file" "$url"
+done