fix: starters/gatsby-starter-theme/package.json & starters/gatsby-sta…

…rter-theme/package-lock.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-ANSIREGEX-1583908
- https://snyk.io/vuln/SNYK-JS-AXIOS-1038255
- https://snyk.io/vuln/SNYK-JS-AXIOS-1579269
- https://snyk.io/vuln/SNYK-JS-ENGINEIO-1056749
- https://snyk.io/vuln/SNYK-JS-GLOBPARENT-1016905
- https://snyk.io/vuln/SNYK-JS-NTHCHECK-1586032
- https://snyk.io/vuln/SNYK-JS-POSTCSS-1255640
- https://snyk.io/vuln/SNYK-JS-REACTDEVUTILS-1083268
- https://snyk.io/vuln/SNYK-JS-WS-1296835
- https://snyk.io/vuln/SNYK-JS-XMLHTTPREQUESTSSL-1082936
- https://snyk.io/vuln/SNYK-JS-XMLHTTPREQUESTSSL-1255647