Warn that sudo is required to explain password prompt.

eris/eris/__main__.py

@@ -1140,8 +1140,9 @@ def check_arguments():
         os.environ["ERIS_CONFIG"] = config_path
     import eris.tools as tools
     if arguments["--apt-install-tools"]:
+        print("Installing all tools… (requires sudo)")
         subprocess.run(["sudo", "apt", "-y", "install"] + sorted(tools.dependencies()), check=True)
-        print("Installed all tools.")
+        print("Done.")
         sys.exit(0)
     if arguments["--info"]:
         print_tool_info()