Fix mypy type errors in render.py by annotating renderable variable

src/rp/render.py

@@ -4,7 +4,7 @@ from __future__ import annotations
 
 from dataclasses import dataclass
 
-from rich.console import Console
+from rich.console import Console, RenderableType
 from rich.json import JSON as RichJSON
 from rich.markdown import Markdown
 from rich.syntax import Syntax
@@ -36,6 +36,7 @@ def render(
 
         use_pager = sys.stdout.isatty()
 
+    renderable: RenderableType
     if file_type in _MARKDOWN_TYPES:
         renderable = Markdown(content)
     elif file_type in _JSON_TYPES: