Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: auscyber

nix/shell-plugins.nix

@@ -51,7 +51,7 @@ let
             echo "ERROR: Configured plugin '$plugin' is not supported by this op binary (\`${opPkg.name or "op"}\`)." >&2
             missing=1
           fi
-        done < ${configuredFile}
+        done < "${configuredFile}"
 
         if [ "$missing" -ne 0 ]; then
           echo "" >&2