docs: drop obsolete compat boilerplate from the examples

`from __future__ import annotations` does nothing on the 3.10+ range
this package supports, so the examples readers copy from should not
carry it. Also removes the now-pointless FA lint selection and the
python2-era shebang in examples.py.

Author: wolph

README.md

@@ -84,8 +84,6 @@ sweeps sky blue into fuchsia. The scan bar has no percentage to sweep
 unchanging cyan instead.
 """
 
-from __future__ import annotations
-
 import sys
 import time
 
@@ -161,8 +159,6 @@ the bar instead:
 ```python
 """A build log printing above a progress bar without corrupting it."""
 
-from __future__ import annotations
-
 import time
 
 import progressbar
@@ -202,8 +198,6 @@ thread, and waits for all of them on exit:
 ```python
 """Two named bars progressing at different rates in one terminal."""
 
-from __future__ import annotations
-
 import sys
 import time
 
@@ -275,8 +269,6 @@ Inside a task, `progressbar.current_task_bar()` hands back that task's
 own bar so it can report sub-progress too.
 """
 
-from __future__ import annotations
-
 import sys
 import time
 
@@ -353,8 +345,6 @@ with a counter instead of a percentage:
 ```python
 """A bar for work whose total is not known up front."""
 
-from __future__ import annotations
-
 import time
 
 import progressbar

docs/examples/howto/colors.py

@@ -7,8 +7,6 @@
 as a single unchanging color instead.
 """
 
-from __future__ import annotations
-
 import time
 
 import progressbar

docs/examples/howto/custom_widget.py

@@ -7,8 +7,6 @@
 current phase instead of showing a percentage.
 """
 
-from __future__ import annotations
-
 import time
 
 import progressbar

docs/examples/howto/dynamic_messages.py

@@ -6,8 +6,6 @@
 from the same value, to show they behave identically.
 """
 
-from __future__ import annotations
-
 import random
 import time
 

docs/examples/howto/file_transfer.py

@@ -8,8 +8,6 @@
 step than most examples in this set.
 """
 
-from __future__ import annotations
-
 import random
 import time
 

docs/examples/howto/iterable_wrapper.py

@@ -6,8 +6,6 @@
 prefix and want to reuse it as a wrapper.
 """
 
-from __future__ import annotations
-
 import time
 
 import progressbar

docs/examples/howto/logging_integration.py

@@ -10,8 +10,6 @@
 handler) in a `finally`, since both mutate process-global state.
 """
 
-from __future__ import annotations
-
 import logging
 import sys
 import time

docs/examples/howto/multibar.py

@@ -9,8 +9,6 @@
 disappearing -- `remove_finished` defaults to an hour.
 """
 
-from __future__ import annotations
-
 import random
 import sys
 import time

docs/examples/howto/multibar_line_offset.py

@@ -7,8 +7,6 @@
 wherever it already is.
 """
 
-from __future__ import annotations
-
 import random
 import time
 

docs/examples/howto/non_tty.py

@@ -12,8 +12,6 @@
 stay on screen.
 """
 
-from __future__ import annotations
-
 import time
 
 import progressbar