fix(cli): Support passing numeric args to prisma

[Tobbe]

Without this fix you couldn't set a custom port for prisma studio

yarn rw prisma studio --port 8917
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TypeError: value.split is not a function
    at handler (/Users/tobbe/tmp/rw-prisma-studio-port/node_modules/@redwoodjs/cli/dist/commands/prismaHandler.js:76:13)
    at Object.handler (/Users/tobbe/tmp/rw-prisma-studio-port/node_modules/@redwoodjs/cli/dist/commands/prisma.js:46:10)
    at async runYargs (/Users/tobbe/tmp/rw-prisma-studio-port/node_modules/@redwoodjs/cli/dist/index.js:153:3)
    at async /Users/tobbe/tmp/rw-prisma-studio-port/node_modules/@redwoodjs/cli/dist/index.js:105:7
    at async main (/Users/tobbe/tmp/rw-prisma-studio-port/node_modules/@redwoodjs/cli/dist/index.js:94:3)