Update Go to 1.13.7

[mikemadden42]

What does this PR do?

go1.13.7 (released 2020/01/28) includes two security fixes to the crypto/x509 package. See the Go 1.13.7 milestone on the issue tracker for details.

Why is it important?

go 1.13.7 fixes two important security issues.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works

Author's Checklist

• run beats-ci/package passes

How to test this PR locally

• make release-manager-release passes
• make release-manager-snapshot passes

Related issues

• Update Go to 1.13.7 golang-crossbuild#40

Use cases

Screenshots

Logs

[mikemadden42]

run beats-ci/package

[mikemadden42]

run beats-ci/package

[ycombinator]

LGTM.

[mikemadden42]

FYI, packaging jobs have been failing for sometime in master with a similar error. master in this case was still using go 1.13.6.

https://beats-ci.elastic.co/job/elastic+beats+master+multijob-package-linux/339/console

13:31:13 package ran for 10m38.708294233s
13:31:13 make[1]: Leaving directory `/var/lib/jenkins/workspace/elastic+beats+master+multijob-package-linux/src/github.com/elastic/beats/x-pack/auditbeat'
13:31:13 make[1]: Entering directory `/var/lib/jenkins/workspace/elastic+beats+master+multijob-package-linux/src/github.com/elastic/beats/x-pack/dockerlogbeat'
13:31:13 mage package
13:31:14 2020/01/29 13:31:14 Found Elastic Beats dir at /var/lib/jenkins/workspace/elastic+beats+master+multijob-package-linux/src/github.com/elastic/beats
13:43:51 Error: runtime error: invalid memory address or nil pointer dereference

[mikemadden42]

This may be related to these updates:
https://beats-ci.elastic.co/job/elastic+beats+master+multijob-package-linux/310/changes

[mikemadden42]

These are the type of errors I'm seeing in the beats-ci/package job:

13:31:03 >> Testing package contents
13:31:13 package ran for 10m38.708294233s
13:31:13 make[1]: Leaving directory `/var/lib/jenkins/workspace/elastic+beats+master+multijob-package-linux/src/github.com/elastic/beats/x-pack/auditbeat'
13:31:13 make[1]: Entering directory `/var/lib/jenkins/workspace/elastic+beats+master+multijob-package-linux/src/github.com/elastic/beats/x-pack/dockerlogbeat'
13:31:13 mage package
13:31:14 2020/01/29 13:31:14 Found Elastic Beats dir at /var/lib/jenkins/workspace/elastic+beats+master+multijob-package-linux/src/github.com/elastic/beats
13:43:51 Error: runtime error: invalid memory address or nil pointer dereference
13:43:51 make[1]: *** [release] Error 1

[mikemadden42]

Fix for the nil pointer issue:
#15935