build: ts-toolbelt version is fixed at 6.15.4

npm/ng-packs/package.json

@@ -88,7 +88,7 @@
     "snq": "^1.0.3",
     "symlink-manager": "^1.5.0",
     "ts-node": "~7.0.0",
-    "ts-toolbelt": "^6.9.9",
+    "ts-toolbelt": "6.15.4",
     "tsickle": "^0.38.1",
     "tslint": "~6.1.0",
     "typescript": "~3.9.5",

npm/ng-packs/yarn.lock

@@ -13241,6 +13241,11 @@ ts-pnp@^1.1.6:
   resolved "https://registry.yarnpkg.com/ts-pnp/-/ts-pnp-1.2.0.tgz#a500ad084b0798f1c3071af391e65912c86bca92"
   integrity sha512-csd+vJOb/gkzvcCHgTGSChYpy5f1/XKNsmvBGO4JXS+z1v2HobugDz4s1IeFXM3wZB44uczs+eazB5Q/ccdhQw==
 
+ts-toolbelt@6.15.4:
+  version "6.15.4"
+  resolved "https://registry.yarnpkg.com/ts-toolbelt/-/ts-toolbelt-6.15.4.tgz#f7fad584e197d0f495f77b5e3ee75a8f4c4dd3da"
+  integrity sha512-Ifp2yNo4I8q5UwNARUBMnBiFpv5DEtTbCtS8RCjjLOz+PNcThbjUsPJCK3hRnz0dTygM1Fi3Mgvnt/DoKUTU2g==
+
 ts-toolbelt@^6.9.9:
   version "6.15.5"
   resolved "https://registry.yarnpkg.com/ts-toolbelt/-/ts-toolbelt-6.15.5.tgz#cb3b43ed725cb63644782c64fbcad7d8f28c0a83"