Add entrypoint for fastapi application

Signed-off-by: vjanz <valon.januzaj98@gmail.com>

fastapi/app/main.py

@@ -0,0 +1,8 @@
+from fastapi import FastAPI
+
+app = FastAPI()
+
+
+@app.get("/")
+def hello_world():
+    return {"message": "OK"}