[Bug] Fix error when opening the website link

The [website](https://eventstack.onrender.com/) seems to output the following:

```py
Traceback (most recent call last):
File "/opt/render/project/src/.venv/lib/python3.13/site-packages/tornado/web.py", line 1846, in _execute
result = method(*self.path_args, **self.path_kwargs)
File "/opt/render/project/src/main.py", line 28, in get
self.render("index.html", user=user)
~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^
File "/opt/render/project/src/.venv/lib/python3.13/site-packages/tornado/web.py", line 994, in render
html = self.render_string(template_name, **kwargs)
File "/opt/render/project/src/.venv/lib/python3.13/site-packages/tornado/web.py", line 1140, in render_string
t = loader.load(template_name)
File "/opt/render/project/src/.venv/lib/python3.13/site-packages/tornado/template.py", line 446, in load
self.templates[name] = self._create_template(name)
~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/opt/render/project/src/.venv/lib/python3.13/site-packages/tornado/template.py", line 477, in _create_template
template = Template(f.read(), name=name, loader=self)
File "/opt/render/project/src/.venv/lib/python3.13/site-packages/tornado/template.py", line 318, in __init__
self.file = _File(self, _parse(reader, self))
~~~~~~^^^^^^^^^^^^^^
File "/opt/render/project/src/.venv/lib/python3.13/site-packages/tornado/template.py", line 1021, in _parse
block_body = _parse(reader, template, operator, in_loop)
File "/opt/render/project/src/.venv/lib/python3.13/site-packages/tornado/template.py", line 1045, in _parse
reader.raise_parse_error("unknown operator: %r" % operator)
~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/opt/render/project/src/.venv/lib/python3.13/site-packages/tornado/template.py", line 838, in raise_parse_error
raise ParseError(msg, self.name, self.line)
tornado.template.ParseError: unknown operator: 'endblock' at index.html:3
```

@abhirajadhikary06 Assign the issue to me and I'll work on it.