build: Update WASM Rego test generation setup (#6707)

This change updates the WASM Rego test generation docker
command to address CVE-2022-24765 in Git which could cause
it to execute arbitrary commands.

The error was seen when running the `make wasm-rego-test` target on
darwin/arm64.

Fixes: #6703

Signed-off-by: Ashutosh Narkar <anarkar4387@gmail.com>