Do not use term.formatter()

This does not work with blessed from Debian/buster:

  Traceback (most recent call last):
    File "/usr/lib/python3/dist-packages/blessed/formatters.py", line 82, in __call__
      attr = curses.tparm(self.encode('latin1'), *args).decode('latin1')
  TypeError: an integer is required (got type str)

  During handling of the above exception, another exception occurred:

  Traceback (most recent call last):
    File "/usr/bin/pg_activity", line 260, in <module>
      ui.main(options)
    File "/usr/lib/python3/dist-packages/pgactivity/ui.py", line 113, in main
      width=width,
    File "/usr/lib/python3/dist-packages/pgactivity/widgets.py", line 15, in boxed
      border_formatter = term.formatter(border_color)
    File "/usr/lib/python3/dist-packages/blessed/formatters.py", line 92, in __call__
      self._name, args, err))
  TypeError: A native or nonexistent capability template, 'formatter' received invalid argument ('yellow',): an integer is required (got type str). You probably misspelled a formatting call like `bright_red'

pgactivity/ui.py

@@ -97,7 +97,7 @@ def main(
                         keys.PROCESS_CANCEL: ("cancel", "yellow"),
                         keys.PROCESS_KILL: ("terminate", "red"),
                     }[key]
-                    action_formatter = term.formatter(color)
+                    action_formatter = getattr(term, color)
                     pids = pg_procs.selected
                     if len(pids) > 1:
                         ptitle = f"processes {', '.join((str(p) for p in pids))}"

pgactivity/widgets.py

@@ -12,7 +12,7 @@ def boxed(
     width: Optional[int] = None,
 ) -> str:
     border_width = term.length(content) + 2
-    border_formatter = term.formatter(border_color)
+    border_formatter = getattr(term, border_color)
     lines = [
         border_formatter("┌" + "─" * border_width + "┐"),
         " ".join([border_formatter("│") + term.normal, content, border_formatter("│")]),