Ignore ca-bundle created by @php-wasm/cli (#88)

## Motivation for the change, related issues

When `@php-wasm/cli` runs, it dynamically creates a `ca-bundle.crt` file
derived from the Node.js `tls` module. We don't want to see this as an
untracked file from `git status`.

## Implementation details

Add the file to .gitignore.

## Testing Instructions (or ideally a Blueprint)

- Run `npx nx dev php-wasm-cli "-r 'echo \"huzzah\n\";'"`
- Use `fine packages/php-wasm/cli -name ca-bundle.crt` to confirm that
ca-bundle.crt exists.
- Run `git status` and confirm the file is not visible.

Author: brandonpayton

.gitignore

@@ -60,3 +60,8 @@ php.js.bak
 **/test-results/
 **/playwright-report/
 **/blob-report/
+
+# @php-wasm/cli saves this file to disk so PHP has access to it.
+# Since it is dynamically generated from the Node.js TLS module,
+# we do not want to commit it to the repository.
+packages/php-wasm/cli/src/ca-bundle.crt