chore: remove 6.x source code

.github/dependabot.yml

@@ -1,32 +0,0 @@
-version: 2
-updates:
-- package-ecosystem: gomod
-  directory: "/"
-  schedule:
-    interval: daily
-    time: "04:00"
-  open-pull-requests-limit: 10
-  ignore:
-  - dependency-name: github.com/microcosm-cc/bluemonday
-    versions:
-    - 1.0.4
-    - 1.0.5
-    - 1.0.6
-    - 1.0.7
-    - 1.0.8
-  - dependency-name: golang.org/x/text
-    versions:
-    - 0.3.5
-  - dependency-name: github.com/labstack/echo/v4
-    versions:
-    - 4.1.17
-    - 4.2.0
-    - 4.2.1
-  - dependency-name: github.com/sirupsen/logrus
-    versions:
-    - 1.7.0
-    - 1.7.1
-    - 1.8.0
-  - dependency-name: github.com/mafredri/cdp
-    versions:
-    - 0.30.0