corrected shebang to ash

scripts/first_page_image.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/ash
 # Converts the first page of each PDF in /public/publications to a PNG.
 
 PDF_DIR="./public/publications"

scripts/generate_webp.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/ash
 # Converts all JPG and PNG images in /public to WebP format.
 
 PUBLIC_DIR="./public"