reduce to single string format. Fix long line in example for CircuitPython

Author: FoamyGuy

adafruit_pycamera/__init__.py

@@ -827,10 +827,7 @@ def open_next_image(self, extension="jpg", filename_prefix="img"):
         except OSError as exc:  # no SD card!
             raise RuntimeError("No SD card mounted") from exc
         while True:
-            filename = f"/sd/{filename_prefix}%04d.%s" % (
-                self._image_counter,
-                extension,
-            )
+            filename = f"/sd/{filename_prefix}{self._image_counter}.{extension}"
             self._image_counter += 1
             try:
                 os.stat(filename)

examples/timestamp_filename/code.py

@@ -47,10 +47,7 @@
         try:
             pycam.display_message("snap", color=0x00DD00)
             # pylint: disable=line-too-long
-            timestamp = (
-                f"img_{time.localtime().tm_year}-{time.localtime().tm_mon}-{time.localtime().tm_mday}"
-                f"_{time.localtime().tm_hour:02}-{time.localtime().tm_min:02}-{time.localtime().tm_sec:02}_"
-            )
+            timestamp = f"img_{time.localtime().tm_year}-{time.localtime().tm_mon}-{time.localtime().tm_mday}_{time.localtime().tm_hour:02}-{time.localtime().tm_min:02}-{time.localtime().tm_sec:02}_"
             pycam.capture_jpeg(filename_prefix=timestamp)
             pycam.live_preview_mode()
         except TypeError as exception: