fix appveyor build problem

Author: fstab

.appveyor.yml

@@ -5,7 +5,7 @@ os:
     Windows Server 2012 R2
 
 clone_folder:
-    C:\go\src\github.com\fstab\grok_exporter
+    C:\grok_exporter
 
 environment:
     PATH: c:\go\bin;C:\msys64\mingw64\bin;%PATH%
@@ -48,7 +48,7 @@ install:
 # --------------------------------------------------------------------------
 
 build_script:
-    - cd c:\go\src\github.com\fstab\grok_exporter
+    - cd c:\grok_exporter
     - git submodule update --init --recursive
     - set GO111MODULE=on
     - go version

.travis.yml

@@ -1,7 +1,7 @@
 language: go
 
 go:
-  - "1.12"
+  - "1.13"
 
 os:
   - linux

go.mod

@@ -8,3 +8,5 @@ require (
 	github.com/sirupsen/logrus v1.4.2
 	gopkg.in/yaml.v2 v2.2.2
 )
+
+go 1.13