Add deprecation warning for TemplatedConfigLoader and ConfigLoader (#2840)

* Add deprecation warning for TCL and CL

Signed-off-by: Ankita Katiyar <ankitakatiyar2401@gmail.com>

* Update release notes, deprecation warning

Signed-off-by: Ankita Katiyar <ankitakatiyar2401@gmail.com>

---------

Signed-off-by: Ankita Katiyar <ankitakatiyar2401@gmail.com>

Author: ankatiyar

RELEASE.md

@@ -24,6 +24,7 @@
 ## Breaking changes to the API
 
 ## Upcoming deprecations for Kedro 0.19.0
+* `ConfigLoader` and `TemplatedConfigLoader` will be deprecated. Please use `OmegaConfigLoader` instead.
 
 # Release 0.18.11
 

kedro/framework/session/session.py

@@ -8,14 +8,15 @@
 import subprocess
 import sys
 import traceback
+import warnings
 from copy import deepcopy
 from pathlib import Path
 from typing import Any, Iterable
 
 import click
 
 from kedro import __version__ as kedro_version
-from kedro.config import ConfigLoader, MissingConfigException
+from kedro.config import ConfigLoader, MissingConfigException, TemplatedConfigLoader
 from kedro.framework.context import KedroContext
 from kedro.framework.context.context import _convert_paths_to_absolute_posix
 from kedro.framework.hooks import _create_hook_manager
@@ -261,7 +262,15 @@ def load_context(self) -> KedroContext:
         env = self.store.get("env")
         extra_params = self.store.get("extra_params")
         config_loader = self._get_config_loader()
-
+        if isinstance(config_loader, (ConfigLoader, TemplatedConfigLoader)):
+            warnings.warn(
+                f"{type(config_loader).__name__} will be deprecated in Kedro 0.19."
+                f" Please use the OmegaConfigLoader instead. To consult"
+                f" the documentation for OmegaConfigLoader, see here:"
+                f" https://docs.kedro.org/en/stable/configuration/"
+                f"advanced_configuration.html#omegaconfigloader",
+                FutureWarning,
+            )
         context_class = settings.CONTEXT_CLASS
         context = context_class(
             package_name=self._package_name,