fix(root): run private package changed tests

Pass Lerna's private filter so bitgo test changes run in the changed-test CI job.

WAL-1960

Author: zahin-mohammad

package.json

@@ -290,7 +290,7 @@
     "postinstall": "test -n \"$NOYARNPOSTINSTALL\" || lerna run build --stream",
     "lint": "lerna run lint --stream",
     "lint-changed": "lerna run lint --since origin/${GITHUB_REPO_BRANCH:-master}..HEAD --stream",
-    "unit-test-changed": "lerna run unit-test --since $(git merge-base HEAD~ origin/${GITHUB_REPO_BRANCH:-master}) --stream",
+    "unit-test-changed": "lerna run unit-test --since $(git merge-base HEAD~ origin/${GITHUB_REPO_BRANCH:-master}) --private --stream",
     "browser-tests": "lerna run --scope bitgo compile-test && lerna run --scope bitgo browser-test && lerna run --scope @bitgo/web-demo test",
     "gen-coverage-changed": "lerna run gen-coverage --since origin/${GITHUB_REPO_BRANCH:-master}..HEAD --stream --parallel",
     "coverage-changed": "lerna run upload-coverage --since origin/${GITHUB_REPO_BRANCH:-master}..HEAD --stream --parallel --",