Make BigNumber a peer dep, to avoid issues using this library's Types

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@stellar/wallet-sdk",
-  "version": "0.0.8-rc.10",
+  "version": "0.0.8-rc.11",
   "description": "Libraries to help you write Stellar-enabled wallets in Javascript",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
@@ -9,7 +9,8 @@
   "license": "Apache-2.0",
   "prettier": "@stellar/prettier-config",
   "peerDependencies": {
-    "stellar-sdk": "^3.x.x"
+    "stellar-sdk": "^3.x.x",
+    "bignumber.js": "*"
   },
   "scripts": {
     "prepare": "yarn build ; yarn build:commonjs",
@@ -54,6 +55,7 @@
     "@types/sinon": "^7.0.11",
     "babel-jest": "^24.5.0",
     "babel-loader": "^8.0.6",
+    "bignumber.js": "^8.1.1",
     "concurrently": "^4.1.1",
     "husky": "^1.3.1",
     "jest": "^24.7.1",
@@ -80,7 +82,6 @@
     "@ledgerhq/hw-transport-u2f": "^4.48.0",
     "@types/jest": "^24.0.11",
     "@types/stellar-base": "^0.10.2",
-    "bignumber.js": "^8.1.1",
     "change-case": "^3.1.0",
     "lodash": "^4.17.14",
     "query-string": "^6.4.2",