Add golang 1.17.8
Add golang 1.17.8

Adds the latest version of go which [addresses a CVE](https://groups.google.com/g/golang-announce/c/RP1hfrBYVuk)
regarding nested regexes

Background
----------

Router is built on CI machines; the artefact is then [uploaded to S3](https://github.com/alphagov/router/blob/main/Jenkinsfile#L68)
for use in deployment.

In deployment, the artefact is [retrieved from S3](https://github.com/alphagov/govuk-app-deployment/blob/master/router%2Fconfig%2Fdeploy.rb#L30)
and uploaded to the cache machines prior to a restart.

The updated version of golang is [only uploaded to Jenkins and CI agents](https://github.com/alphagov/govuk-puppet/search?q=golang).

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet