Revert "Migrate from deprecated importlib.resources function"

This reverts commit 9ace677.

src/nsidc/metgen/metgen.py

@@ -7,7 +7,7 @@
 import os.path
 import sys
 import uuid
-from importlib.resources import files
+from importlib.resources import open_text
 from pathlib import Path
 from string import Template
 from typing import Callable
@@ -668,14 +668,13 @@ def cnms_body_template():
 def cnms_files_template():
     return initialize_template(constants.CNM_FILES_TEMPLATE)
 
-def _open_text(anchor, name):
-    for t in files(anchor).iterdir():
-        if t.name == name:
-            return t.read_text()
-    return None
 
 def initialize_template(resource_location):
-    return Template(_open_text(*resource_location))
+    with open_text(*resource_location) as template_file:
+        template_str = template_file.read()
+
+    return Template(template_str)
+
 
 def validate(configuration, content_type):
     """
@@ -687,11 +686,12 @@ def validate(configuration, content_type):
     logger = logging.getLogger(constants.ROOT_LOGGER)
     logger.info("")
     logger.info(f"Validating files in {output_file_path}...")
+    with open_text(*schema_resource_location) as sf:
+        schema = json.load(sf)
 
-    schema = json.load(_open_text(*schema_resource_location))
-    # loop through all files and validate each one
-    for json_file in output_file_path.glob("*.json"):
-        apply_schema(schema, json_file, dummy_json)
+        # loop through all files and validate each one
+        for json_file in output_file_path.glob("*.json"):
+            apply_schema(schema, json_file, dummy_json)
 
     logger.info("Validations complete.")
     return True