vault: 0.9.0 -> 0.9.4

Semi-automatic update. These checks were performed:

- built on NixOS
- ran `/nix/store/kp72kh1a4dy4pdj5i4qnngmwz9083yjf-vault-0.9.4/bin/vault -h` got 0 exit code
- ran `/nix/store/kp72kh1a4dy4pdj5i4qnngmwz9083yjf-vault-0.9.4/bin/vault --help` got 0 exit code
- ran `/nix/store/kp72kh1a4dy4pdj5i4qnngmwz9083yjf-vault-0.9.4/bin/vault -v` and found version 0.9.4
- ran `/nix/store/kp72kh1a4dy4pdj5i4qnngmwz9083yjf-vault-0.9.4/bin/vault --version` and found version 0.9.4
- ran `/nix/store/kp72kh1a4dy4pdj5i4qnngmwz9083yjf-vault-0.9.4/bin/vault version` and found version 0.9.4
- found 0.9.4 with grep in /nix/store/kp72kh1a4dy4pdj5i4qnngmwz9083yjf-vault-0.9.4
- found 0.9.4 in filename of file in /nix/store/kp72kh1a4dy4pdj5i4qnngmwz9083yjf-vault-0.9.4

cc "@rushmorem @offline @pradeepchhetri"