Use .env file for credentials used in example.py file

.env.example

@@ -0,0 +1,2 @@
+USERNAME=
+PASSWORD=

.gitignore

@@ -17,3 +17,5 @@ debug.txt
 /.vs/*
 
 .DS_Store
+
+.env

README.md

@@ -13,7 +13,7 @@ Thus, I have created a `debug()` function that runs when `example.py` is execute
 ## How to use api:
 See [example.py](https://github.com/klejejs/python-thermia-online-api/blob/main/example.py) file for examples.
 
-To execute the example file, first run `pip install -r requirements.txt` to install the required dependencies, then run `python3 example.py` to execute the example file. You will be prompted to enter your username and password, and then the example file will run. If do not want to manually enter your credentials every time, you can edit the `credentials.py` file and add your credentials there.
+To execute the example file, first run `pip install -r requirements.txt` to install the required dependencies, then run `python3 example.py` to execute the example file. You will be prompted to enter your username and password, and then the example file will run. If do not want to manually enter your credentials every time, you can make a copy of `.env.example`, save it as a `.env` file, and add your credentials there.
 
 ## Available functions in Thermia class:
 | Function | Description |

example.py

@@ -1,11 +1,20 @@
 from datetime import datetime, timedelta
 from ThermiaOnlineAPI import Thermia
-from credentials import USERNAME, PASSWORD
 
 CHANGE_HEAT_PUMP_DATA_DURING_TEST = (
     False  # Set to True if you want to change heat pump data during test
 )
 
+USERNAME = None
+PASSWORD = None
+
+with open(".env", "r") as env_file:
+    for line in env_file:
+        if line.startswith("USERNAME="):
+            USERNAME = line.split("=")[1].strip()
+        elif line.startswith("PASSWORD="):
+            PASSWORD = line.split("=")[1].strip()
+
 if not USERNAME or not PASSWORD:
     USERNAME = input("Enter username: ")
     PASSWORD = input("Enter password: ")