fix(scripts): replace hardcoded /bin/bash shebangs

Several helper scripts assumes bash is available at /bin/bash. That breaks on systems
such as NixOS, where bash is resolved from PATH instead of a fixed /bin location and
causes failures like `bad interpreter` during `make format`, e.g., on my host machine:

```sh
$ make format

/PX4-Autopilot/Tools/astyle/check_code_style.sh: /PX4-Autopilot/Tools/astyle/fix_code_style.sh: /bin/bash: bad interpreter: No such file or directory
```

This change switches these entrypoints to `#!/usr/bin/env bash` so they locate bash properly.

No functional changes intended.

Signed-off-by: Onur Özkan <work@onurozkan.dev>

Tools/setup/docker-entrypoint.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 GREEN='\033[0;32m'
 NO_COLOR='\033[0m' # No Color