refactor: remove assert statement from non-test files

Usage of `assert` statement in application logic is discouraged. `assert` is removed with compiling to optimized byte code. Consider raising an exception instead. Ideally, `assert` statement should be used only in tests.

src/plugins/nonebot_plugin_githubcard/__init__.py

@@ -29,5 +29,6 @@ def match_link_parts(link):
 async def github_handle(bot: Bot, event: GroupMessageEvent, state: T_State):
     url = match_link_parts(event.get_plaintext())
     imageUrl = await get_github_reposity_information(url)
-    assert (imageUrl != "获取信息失败")
+    if (imageUrl == "获取信息失败"):
+        raise AssertionError
     await github.send(MessageSegment.image(imageUrl))