tests/thirdparty: add crypto/internal/bigmod (#355)

Add test case for avo generator in standard library crypto/internal/bigmod.

https://github.com/golang/go/tree/go1.20rc2/src/crypto/internal/bigmod
https://golang.org/cl/452095
https://words.filippo.io/dispatches/go-1-20-cryptography/

Closes #354

.github/workflows/thirdparty.yml

@@ -25,4 +25,4 @@ jobs:
           persist-credentials: false
       - name: Run Third-Party Tests
         working-directory: tests/thirdparty
-        run: go test -net -suite suite.json
+        run: go test -timeout 15m -args -net -suite suite.json