Update shfmt to v2.6.1

Author: PeterDaveHello

.travis.yml

@@ -44,7 +44,7 @@ jobs:
     services:
       - docker
     script:
-      - docker run -it --rm -v "$(pwd)":/sh -w /sh peterdavehello/shfmt:2.6.0 shfmt -sr -i 2 -l -w -ci .
+      - docker run -it --rm -v "$(pwd)":/sh -w /sh peterdavehello/shfmt:2.6.1 shfmt -sr -i 2 -l -w -ci .
       - git diff --color
       - git diff --stat=220 --color --exit-code