Travis CI: clean up Go versions

.travis.yml

@@ -7,14 +7,15 @@ dist: xenial
 git:
   depth: 300
 
-# Build with the lastest versions of Go 1.7 and later
-# See https://golang.org/dl/
+# Build with the lastest relevant Go versions
+# Relevance is determined from:
+# * https://golang.org/dl/
+# * https://packages.debian.org/search?keywords=golang&searchon=names&exact=1&suite=all&section=all
+# * https://packages.ubuntu.com/search?keywords=golang&searchon=names&exact=1&suite=all&section=all
 go:
-  - 1.9.x
-  - 1.10.x
-  - 1.11.x
-  - 1.12.x
-  - 1.12.x
+  - 1.11.x # Debian 10 "Buster"
+  - 1.12.x # Ubuntu 19.10
+  - 1.13.x # Debian 11 "Bullseye"
   - stable
 
 before_install:

README.md

@@ -93,7 +93,7 @@ as well as in the go-fuse library.
 Compile
 -------
 
-With [go 1.7 or higher](.travis.yml#L12):
+With [go 1.11 or higher](.travis.yml#L12):
 
 	$ go get -d github.com/rfjakob/gocryptfs
 	$ cd $(go env GOPATH)/src/github.com/rfjakob/gocryptfs