Update shell script shebangs

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

lib/scripts/update-keys.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/usr/bin/env -S nix shell nixpkgs#sops -c bash
 
 set -o errexit
 set -o nounset
@@ -18,6 +18,6 @@ find . -type f -name 'sops.yaml' | while IFS= read -r sops_file; do
     -regex '.+\.(yaml|yml|json|env|ini|bin)' \
     ! -name 'sops.yaml' | while IFS= read -r file; do
       echo "$file"
-      nix shell nixpkgs#sops --command sops --config "$sops_file" updatekeys "$file" -y
+      sops --config "$sops_file" updatekeys "$file" -y
     done
 done