Fix docker:build command for non-Linux OS (#190)

Author: bdrhn9

packages/airnode-feed/package.json

@@ -16,7 +16,7 @@
     "clean": "rm -rf coverage dist",
     "dev": "nodemon --ext ts,js,json,env  --exec \"pnpm ts-node src/index.ts\"",
     "docker:build": "docker build --target airnode-feed --tag api3/airnode-feed:latest ../../",
-    "docker:build:amd64": "docker buildx build --platform linux/amd64 --tag api3/airnode-feed:latest ../../",
+    "docker:build:amd64": "docker buildx build --target airnode-feed --platform linux/amd64 --tag api3/airnode-feed:latest ../../",
     "docker:run": "docker run -it --init --volume $(pwd)/config:/app/config --network host --env-file .env --rm api3/airnode-feed:latest",
     "eslint:check": "eslint . --ext .js,.ts --max-warnings 0",
     "eslint:fix": "eslint . --ext .js,.ts --fix",

packages/signed-api/package.json

@@ -16,7 +16,7 @@
     "clean": "rm -rf coverage dist",
     "dev": "nodemon --ext ts,js,json,env --exec \"DEV_SERVER_PORT=${DEV_SERVER_PORT:-8090} pnpm ts-node src/dev-server.ts\"",
     "docker:build": "docker build --target signed-api --tag api3/signed-api:latest ../../",
-    "docker:build:amd64": "docker buildx build --platform linux/amd64 --tag api3/signed-api:latest ../../",
+    "docker:build:amd64": "docker buildx build --target signed-api --platform linux/amd64 --tag api3/signed-api:latest ../../",
     "docker:run": "docker run --publish 8090:80 -it --init --volume $(pwd)/config:/app/config --env-file .env --rm api3/signed-api:latest",
     "eslint:check": "eslint . --ext .js,.ts --max-warnings 0",
     "eslint:fix": "eslint . --ext .js,.ts --fix",