Fix compatibility issues in compile.sh

* Use '/usr/bin/env bash', because not all distros put bash in /bin
  (some in /usr/bin), and with NixOS it's even more complicated. This
  should make it compatible across all distros.
* The 'set -euo pipefail' makes the script exit immediately on error,
  otherwise it tries to continue e.g. running make when the CMake
  configuration failed.
* Change to the directory the script sits in, in case it is ever called
  from another directory.
* With CMake 4.x, declaring compatibility with version 3.5 straight up
  errors. Passing the environment variable fixes this issue. See
  https://gitlab.kitware.com/cmake/cmake/-/issues/26613 and
  https://gitlab.kitware.com/cmake/cmake/-/issues/26698 for more info.
* CMake doesn't always emit Makefiles by default, so use `cmake --build'
  to build using whatever method CMake will choose.
* Compile using all available cores, instead of only using a single CPU
  core.

compile.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 ###############################################################
 # File:          compile.sh
 # Creation Date: 10/11/2022 (DD/MM/YYYY)
@@ -9,26 +9,33 @@
 # Copyright:     LNH team (c) 2022, all rights reserved
 ################################################################
 
+set -euo pipefail
 
+# change directory to the one containing the source code project
+cd "$(dirname "$(realpath "$0")")"
+
+# check available CMake version
 echo "[>] Configuring project with CMake.."
 
 # Clean previous build/ folders if they exist
-rm -rf build/
-mkdir build
-
-# Export the SDK Path before running CMAKE
-export PICO_SDK_PATH=../pico-sdk
+rm -rf build/ || true
+mkdir -p build
 
 # Specify CMAKE where we want the build tree to be at.
 # In our case, the build/ directory.
 # The source directory will be . (the current directory,
 # where the CMakeLists.txt is located).
-cmake -DCMAKE_BUILD_TYPE:STRING=RelWithDebInfo -B build/ .
+PICO_SDK_PATH=../pico-sdk \
+CMAKE_POLICY_VERSION_MINIMUM=3.5 \
+	cmake -DCMAKE_BUILD_TYPE:STRING=RelWithDebInfo \
+		-B build/ .
 
 echo "[>] Building FIRMWARE: "
 
 # Go and build the firmware
-cd build
-make
+PICO_SDK_PATH=../pico-sdk \
+CMAKE_POLICY_VERSION_MINIMUM=3.5 \
+CMAKE_BUILD_PARALLEL_LEVEL="$(nproc)" \
+	cmake --build build
 
 echo "[>] Build completed. Find the DSpico.uf2 file inside build/ folder"