Bump acorn from 6.1.0 to 6.1.1

Bumps [acorn](https://github.com/acornjs/acorn) from 6.1.0 to 6.1.1.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](acornjs/acorn@6.1.0...6.1.1)

Signed-off-by: dependabot[bot] <support@dependabot.com>

yarn.lock

@@ -468,9 +468,9 @@ acorn@^5.0.0, acorn@^5.3.0:
   integrity sha512-cJrKCNcr2kv8dlDnbw+JPUGjHZzo4myaxOLmpOX8a+rgX94YeTcTMv/LFJUSByRpc+i4GgVnnhLxvMu/2Y+rqw==
 
 acorn@^6.0.5, acorn@^6.0.7:
-  version "6.1.0"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.1.0.tgz#b0a3be31752c97a0f7013c5f4903b71a05db6818"
-  integrity sha512-MW/FjM+IvU9CgBzjO3UIPCE2pyEwUsoFl+VGdczOPEdxfGFjuKny/gN54mOuX7Qxmb9Rg9MCn2oKiSUeW+pjrw==
+  version "6.1.1"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.1.1.tgz#7d25ae05bb8ad1f9b699108e1094ecd7884adc1f"
+  integrity sha512-jPTiwtOxaHNaAPg/dmrJ/beuzLRnXtB0kQPQ8JpotKJgTB6rX6c8mlf315941pyjBSaPg8NHXS9fhP4u17DpGA==
 
 ajv-errors@^1.0.0:
   version "1.0.1"