Adapt crewai tool install <tool> to uv (#1481)

This commit updates the tool install comamnd to uv's new custom index
feature.

Related: https://github.com/astral-sh/uv/pull/7746/

tests/cli/tools/test_main.py

@@ -75,8 +75,8 @@ def test_install_success(mock_get, mock_subprocess_run):
         [
             "uv",
             "add",
-            "--extra-index-url",
-            "https://app.crewai.com/pypi/sample-repo",
+            "--index",
+            "sample-repo=https://example.com/repo",
             "sample-tool",
         ],
         capture_output=False,