cli (base): use XTERM_VERSION to detect XTerm:

Using `TERM` is not good as it is used by other terminal emulators which are incompatible
with ANSI sequences (seen with `cool-retro-term`).

sat_frontends/jp/base.py

@@ -131,7 +131,7 @@ class LiberviaCli:
         if ((sys.stdin.isatty() and sys.stdout.isatty()
              and (
                  # XTerm
-                 os.getenv("TERM", "") in {"xterm"}
+                 os.getenv("XTERM_VERSION")
                  # Konsole
                  or os.getenv("KONSOLE_VERSION")
                  # All VTE based terminals