CI: fixing the files to be complient with pre-commit hooks

components/esp_modem/examples/linux_modem/README.md

@@ -20,4 +20,4 @@ over PPPoS, i.e. over the modem serial line.
 
 ### Supported IDF versions
 
-This example (using the default CMake IDF build system) is only supported from `v4.4`, since is uses `idf.py`'s linux target.  
+This example (using the default CMake IDF build system) is only supported from `v4.4`, since is uses `idf.py`'s linux target.

components/esp_modem/examples/linux_modem/main/modem_main.cpp

@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Unlicense OR CC0-1.0
+ */
 #include <memory>
 #include <cassert>
 #include <unistd.h>
@@ -79,4 +84,4 @@ int main()
 
     usleep(15'000'000);
     esp_netif_destroy(tun_netif);
-}
+}