add .editorconfig and remove static indent shfmt setting from lint action

.editorconfig

@@ -0,0 +1,9 @@
+[*]
+indent_style = space
+indent_size = 4
+tab_width = 8
+end_of_line = lf
+trim_trailing_whitespace = true
+insert_final_newline = true
+function_next_line = true
+switch_case_indent = true

.github/workflows/lint.yml

@@ -20,7 +20,7 @@ jobs:
     - name: run shfmt
       uses: luizm/action-sh-checker@v0.3.0
       env:
-        SHFMT_OPTS: -i 4 -d
+        SHFMT_OPTS: -d
       with:
         sh_checker_comment: false
         sh_checker_shellcheck_disable: true