chore: npm-check-updates && yarn upgrade (#12911)

Ran npm-check-updates and yarn upgrade to keep the `yarn.lock` file up-to-date.

Closes aws/aws-cdk#12536

packages/decdk/package.json

@@ -210,18 +210,18 @@
     "@aws-cdk/yaml-cfn": "0.0.0",
     "constructs": "^3.2.0",
     "fs-extra": "^9.1.0",
-    "jsii-reflect": "^1.15.0",
+    "jsii-reflect": "^1.20.1",
     "jsonschema": "^1.4.0",
     "yaml": "1.10.0",
     "yargs": "^16.2.0"
   },
   "devDependencies": {
     "@types/fs-extra": "^8.1.1",
-    "@types/jest": "^26.0.15",
+    "@types/jest": "^26.0.20",
     "@types/yaml": "1.9.7",
-    "@types/yargs": "^15.0.10",
+    "@types/yargs": "^15.0.13",
     "jest": "^26.6.3",
-    "jsii": "^1.15.0"
+    "jsii": "^1.20.1"
   },
   "keywords": [
     "aws",