use r+f string

pre_commit/languages/r.py

@@ -92,7 +92,9 @@ def install_environment(
         cmd_output_b(
             'Rscript', '--vanilla', '-e',
             f"""\
-            prefix_dir <- "{os.path.normpath(prefix.prefix_dir)}"
+            prefix_dir <- "{
+                prefix.prefix_dir.encode('unicode_escape').decode()
+            }"
             missing_pkgs <- setdiff(
                 "renv", unname(installed.packages()[, "Package"])
             )