[skip ci] fix favicon generator dev script

tools/scripts/favicon-generator.dev.sh

-secrets_file="./configs/envs/.env.secrets"
 favicon_folder="./public/assets/favicon/"
 master_url="https://raw.githubusercontent.com/blockscout/frontend/main/tools/scripts/favicon.svg"
 
-if [ ! -f "$secrets_file" ]; then
-    echo "Error: File '$secrets_file' not found."
-    exit 1
-fi
-
 dotenv \
   -v MASTER_URL=$master_url \
-  -- bash -c 'cd ./deploy/tools/favicon-generator && node "$(dirname "$0")/index.js"'
+  -- bash -c 'cd ./deploy/tools/favicon-generator && yarn install --frozen-lockfile && node "$(pwd)/index.js"'
 
 if [ -d "$favicon_folder" ]; then
   rm -r "$favicon_folder"