avoid private tomlkit method

src/poetry/console/commands/add.py

@@ -125,9 +125,7 @@ The add command adds required packages to your <comment>pyproject.toml</> and in
             section = poetry_content["dependencies"]
         else:
             if "group" not in poetry_content:
-                poetry_content.value._insert_after(
-                    "dependencies", "group", table(is_super_table=True)
-                )
+                poetry_content["group"] = table(is_super_table=True)
 
             groups = poetry_content["group"]
             if group not in groups:

tests/console/commands/test_remove.py

@@ -67,9 +67,7 @@ baz = "^1.0.0"
 """
     )
     content["tool"]["poetry"]["dependencies"]["foo"] = "^2.0.0"
-    content["tool"]["poetry"].value._insert_after(
-        "dependencies", "group", groups_content["tool"]["poetry"]["group"]
-    )
+    content["tool"]["poetry"]["group"] = groups_content["tool"]["poetry"]["group"]
     app.poetry.file.write(content)
 
     app.poetry.package.add_dependency(Factory.create_dependency("foo", "^2.0.0"))
@@ -128,9 +126,7 @@ baz = "^1.0.0"
 """
     )
     content["tool"]["poetry"]["dependencies"]["foo"] = "^2.0.0"
-    content["tool"]["poetry"].value._insert_after(
-        "dependencies", "group", groups_content["tool"]["poetry"]["group"]
-    )
+    content["tool"]["poetry"]["group"] = groups_content["tool"]["poetry"]["group"]
     app.poetry.file.write(content)
 
     app.poetry.package.add_dependency(Factory.create_dependency("foo", "^2.0.0"))
@@ -189,9 +185,7 @@ baz = "^1.0.0"
 """
     )
     content["tool"]["poetry"]["dependencies"]["foo"] = "^2.0.0"
-    content["tool"]["poetry"].value._insert_after(
-        "dependencies", "group", groups_content["tool"]["poetry"]["group"]
-    )
+    content["tool"]["poetry"]["group"] = groups_content["tool"]["poetry"]["group"]
     app.poetry.file.write(content)
 
     app.poetry.package.add_dependency(Factory.create_dependency("foo", "^2.0.0"))