Remove duplicated script: scripts/gen-changelog exists

scripts/changelog

@@ -1,12 +0,0 @@
-#!/usr/bin/env bash
-
-if [[ -z "$1" ]]; then
-    echo "No rev list given"
-    exit 1
-fi
-
-for rev in $(git rev-list $1); do
-    if git notes --ref=changelog list $rev &> /dev/null; then
-        git log -n 1 --show-notes=* --pretty="format:* %N" $rev
-    fi
-done