fix: package.json & yarn.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-TAR-15038581
- https://snyk.io/vuln/SNYK-JS-LODASH-15053838

Author: snyk-bot

package.json

@@ -28,8 +28,8 @@
     "graphql-relay": "^0.6.0",
     "graphql-resolve-batch": "^1.0.2",
     "graphql-subscriptions": "^1.0.0",
-    "grpc": "^1.24.3",
-    "js-xdr": "^1.1.0",
+    "grpc": "^1.24.11",
+    "js-xdr": "^3.1.2",
     "minimist": "^1.2.3",
     "object-dig": "^0.1.3",
     "pg": "^8.2.1",
@@ -38,7 +38,7 @@
     "progress": "^2.0.3",
     "retry": "^0.12.0",
     "squel": "^5.12.2",
-    "stellar-base": "^3.0.4",
+    "stellar-base": "^13.1.0",
     "typeorm": "^0.2.17",
     "typescript-memoize": "^1.0.0-alpha.3",
     "winston": "^3.0.0"