fix: script had bad interpreter path due to changes for linting (#159)

Linting changes introduced in #158 changed the shell on the script from
the universally available `/bin/sh` to `/usr/bin/env/bash` which does
not exist.

This change points the script to `/bin/bash` which should exist in GHA.

Author: bradegler

.github/generate_version_checksums.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env/bash
+#!/bin/bash
 
 set -euo pipefail