fix: packages/grafana-toolkit/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-BRACES-6838727
- https://snyk.io/vuln/SNYK-JS-INFLIGHT-6095116
- https://snyk.io/vuln/SNYK-JS-MICROMATCH-6838728
- https://snyk.io/vuln/SNYK-JS-UNSETVALUE-2400660

packages/grafana-toolkit/package.json

@@ -71,7 +71,7 @@
     "html-loader": "0.5.5",
     "html-webpack-plugin": "^3.2.0",
     "inquirer": "^6.3.1",
-    "jest": "26.6.3",
+    "jest": "27.0.0",
     "jest-canvas-mock": "2.3.0",
     "jest-coverage-badges": "^1.1.2",
     "jest-environment-jsdom-fifteen": "^1.0.2",