✨ Add docs and tests for Python 3.9 and Python 3.10 (#3712)

Co-authored-by: Thomas Grainger <tagrain@gmail.com>

docs_src/request_files/tutorial002_py39.py

@@ -0,0 +1,31 @@
+from fastapi import FastAPI, File, UploadFile
+from fastapi.responses import HTMLResponse
+
+app = FastAPI()
+
+
+@app.post("/files/")
+async def create_files(files: list[bytes] = File(...)):
+    return {"file_sizes": [len(file) for file in files]}
+
+
+@app.post("/uploadfiles/")
+async def create_upload_files(files: list[UploadFile] = File(...)):
+    return {"filenames": [file.filename for file in files]}
+
+
+@app.get("/")
+async def main():
+    content = """
+<body>
+<form action="/files/" enctype="multipart/form-data" method="post">
+<input name="files" type="file" multiple>
+<input type="submit">
+</form>
+<form action="/uploadfiles/" enctype="multipart/form-data" method="post">
+<input name="files" type="file" multiple>
+<input type="submit">
+</form>
+</body>
+    """
+    return HTMLResponse(content=content)