fix loading Nix Flake shell via direnv

Signed-off-by: Jakub Sokołowski <[email protected]>

.envrc

@@ -1,16 +1,4 @@
-NBS_ONLY_LOAD_ENV_VARS=1 source env.sh
-
-if command -v nix > /dev/null
-then
-  export NIMBUS_NIX_ENV=1
-
-  cd installer/nix
-  # watch_file tells direnv that changes to any of the watched files
-  # should trigger a re-evalution of the environment
-  watch_file flake.nix
-  watch_file flake.lock
-  watch_file shell.nix
-
-  mkdir -p .flake-profiles
-  eval "$(nix print-dev-env --profile ".flake-profiles/profile")"
+if ! has nix_direnv_version || ! nix_direnv_version 3.0.6; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/3.0.6/direnvrc" "sha256-RYcUJaRMf8oF5LznDrlCXbkOQrywm0HDv1VjYGaJGdM="
 fi
+use flake