go.mod: bump go release to 1.14 (#113)

Release 1.12 is no longer supported.

Signed-off-by: Kent R. Spillner <[email protected]>

Author: sl4mmy

go.mod

@@ -1,6 +1,6 @@
 module github.com/ktrysmt/go-bitbucket
 
-go 1.12
+go 1.14
 
 require (
 	github.com/golang/protobuf v1.0.0