Add GET endpoint for /planets

endpoints/planets.get.py

@@ -0,0 +1,14 @@
+# Entity: Planet
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+from app.api.db.database import get_db
+
+router = APIRouter()
+
+@router.get("/planets", response_model=List[PlanetSchema])
+async def get_planets(
+    db: Session = Depends(get_db)
+):
+    planets = db.query(Planet).all()
+    return planets