fix: use context manager in urllib.request examples

Author: Mr-Sunglasses

Doc/library/urllib.request.rst

@@ -1297,10 +1297,8 @@ Use of Basic HTTP Authentication::
    opener = urllib.request.build_opener(auth_handler)
    # ...and install it globally so it can be used with urlopen.
    urllib.request.install_opener(opener)
-   try:
-      r = urllib.request.urlopen('http://www.example.com/login.html')
-   finally:
-      r.close()
+   with urllib.request.urlopen('http://www.example.com/login.html') as r:
+      print(r.read().decode('utf-8'))
 
 :func:`build_opener` provides many handlers by default, including a
 :class:`ProxyHandler`.  By default, :class:`ProxyHandler` uses the environment
@@ -1329,10 +1327,9 @@ Use the *headers* argument to the :class:`Request` constructor, or::
    req.add_header('Referer', 'http://www.python.org/')
    # Customize the default User-Agent header value:
    req.add_header('User-Agent', 'urllib-example/0.1 (Contact: . . .)')
-   try:
-      r = urllib.request.urlopen(req)
-   finally:
-      r.close()
+   with urllib.request.urlopen(req) as r:
+      print(r.read().decode('utf-8'))
+
 
 :class:`OpenerDirector` automatically adds a :mailheader:`User-Agent` header to
 every :class:`Request`.  To change this::