Update logrus to v1.6.0

Fixes #3223 by bumping logrus to v1.6.0, which in turn bumps
github.com/konsorten/go-windows-terminal-sequences to v1.0.3
wherein the fix to bad pointer is found.

Signed-off-by: Andreas Hassing <andreas@famhassing.dk>

vendor/github.com/sirupsen/logrus/appveyor.yml

@@ -1,14 +1,14 @@
-version: "{build}"
-platform: x64
-clone_folder: c:\gopath\src\github.com\sirupsen\logrus
-environment:  
-  GOPATH: c:\gopath
-branches:  
-  only:
-    - master
-install:  
-  - set PATH=%GOPATH%\bin;c:\go\bin;%PATH%
-  - go version
-build_script:  
-  - go get -t
-  - go test
+version: "{build}"
+platform: x64
+clone_folder: c:\gopath\src\github.com\sirupsen\logrus
+environment:
+  GOPATH: c:\gopath
+branches:
+  only:
+    - master
+install:
+  - set PATH=%GOPATH%\bin;c:\go\bin;%PATH%
+  - go version
+build_script:
+  - go get -t
+  - go test