firmware: use typing.List instead of list for type hint

list is not subscriptable in Python 3.8.

Fixes:

    File "/home/runner/work/pybricksdev/pybricksdev/pybricksdev/firmware.py", line 37, in <module>
        "mpy-cross-options": list[str],
    TypeError: 'type' object is not subscriptable

Author: dlech

CHANGELOG.md

@@ -16,6 +16,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Move/renamed `pybricksdev.flash.create_firmware` to `pybricksdev.firmware.create_firmware_blob`.
 - Changed return value of `pybricksdev.firmware.create_firmware_blob` to include license text.
 
+### Fixed
+- Fixed "object is not subscriptable" error in Python 3.8 in `firmware` module.
+
 ## [1.0.0-alpha.30] - 2022-08-26
 
 ### Added

pybricksdev/firmware.py

@@ -11,7 +11,7 @@
 import struct
 import sys
 import zipfile
-from typing import BinaryIO, Literal, Optional, Tuple, TypedDict, Union
+from typing import BinaryIO, List, Literal, Optional, Tuple, TypedDict, Union
 
 
 if sys.version_info < (3, 10):
@@ -34,7 +34,7 @@ class FirmwareMetadataV100(
             "device-id": Literal[0x40, 0x41, 0x80, 0x81],
             "checksum-type": Literal["sum", "crc32"],
             "mpy-abi-version": int,
-            "mpy-cross-options": list[str],
+            "mpy-cross-options": List[str],
             "user-mpy-offset": int,
             "max-firmware-size": int,
         },