chore: Python 2 to 3 migration.

Dockerfile

@@ -1,4 +1,4 @@
-FROM python:2.7.18
+FROM python:3.9
 
 EXPOSE 5000
 
@@ -14,4 +14,4 @@ RUN pip install -r requirements.txt
 
 ADD . /app/
 
-CMD ["python", "app.py"]
+CMD ["python3", "app.py"]

Procfile

@@ -1 +1 @@
-web: python app.py
+web: python3 app.py

README.md

@@ -11,10 +11,10 @@ However, it is still functional with the `scalingo-18` stack.
 ## Run Locally
 
 ```shell
-virtualenv
-. bin/activate
+python3 -m venv venv
+. venv/bin/activate
 pip install -r requirements.txt
-python app.py
+python3 app.py
 ```
 
 ## Deploy via Git
@@ -32,4 +32,4 @@ The application is running at this URL: https://<name_of_your_app>.osc-fr1.scali
 
 ## Deploy via one-click
 
-[![Deploy to Scalingo](https://cdn.scalingo.com/deploy/button.svg)](https://my.scalingo.com/deploy)
+[![Deploy to Scalingo](https://cdn.scalingo.com/deploy/button.svg)](https://my.scalingo.com/deploy)

app.py

@@ -9,8 +9,8 @@ def hello():
     return render_template('index.html')
 
 if __name__ == "__main__":
-    print "Running app"
+    print("Running app")
     port = int(os.environ.get("PORT", 5000))
-    if port <> 5000:
-        print "Using non-standard port %d" % port
-    app.run(host='0.0.0.0', port=port)
+    if port != 5000:
+        print("Using non-standard port %d" % port)
+    app.run(host='0.0.0.0', port=port)

requirements.txt

@@ -1,6 +1,6 @@
-Click==7.0
-Flask==1.0.2
-itsdangerous==1.1.0
-Jinja2==2.11.3
-MarkupSafe==1.1.1
-Werkzeug==0.15.3
+Click==8.0.1
+Flask==2.0.1
+itsdangerous==2.0.1
+Jinja2==3.0.1
+MarkupSafe==2.0.1
+Werkzeug==2.0.1

runtime.txt

@@ -1 +1 @@
-python-2.7.16
+python-3.10.0