[docker-py] Add exec_start overload

Author: roberfi

stubs/docker/docker/api/exec_api.pyi

@@ -115,3 +115,21 @@ class ExecApiMixin:
         socket: Literal[False] = False,
         demux: Literal[False] = False,
     ) -> str: ...
+    @overload
+    def exec_start(
+        self,
+        exec_id: str,
+        detach: bool = False,
+        tty: bool = False,
+        stream: bool = False,
+        socket: bool = False,
+        demux: bool = False,
+    ) -> (
+        str
+        | SocketIO
+        | _BufferedReaderStream
+        | SSHSocket
+        | CancellableStream[str]
+        | CancellableStream[tuple[str | None, str | None]]
+        | tuple[str | None, str | None]
+    ): ...