Use long options for shfmt arguments

Since shfmt now supports long command line options we should use them
as that is our preference. The single quotes for the number of spaces
to indent is changed to double quotes to align with our usual quotation
style.

.pre-commit-config.yaml

@@ -92,14 +92,14 @@ repos:
       - id: shfmt
         args:
           # Indent by two spaces
-          - -i
-          - '2'
+          - --indent
+          - "2"
           # Binary operators may start a line
-          - -bn
+          - --binary-next-line
           # Switch cases are indented
-          - -ci
+          - --case-indent
           # Redirect operators are followed by a space
-          - -sr
+          - --space-redirects
   - repo: https://github.com/detailyang/pre-commit-shell
     rev: 1.0.5
     hooks: