Bump base64 from 0.2.0 to 0.3.0

Bumps [base64](https://github.com/ruby/base64) from 0.2.0 to 0.3.0.
- [Release notes](https://github.com/ruby/base64/releases)
- [Commits](ruby/base64@v0.2.0...v0.3.0)

---
updated-dependencies:
- dependency-name: base64
  dependency-version: 0.3.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Gemfile.lock

@@ -8,7 +8,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     ast (2.4.2)
-    base64 (0.2.0)
+    base64 (0.3.0)
     benchmark (0.4.0)
     benchmark-ips (2.14.0)
     byebug (11.1.3)