Temporary revert GPG feature for semver based retagging (#373)

Feature #343 happens to be a breaking change when enabling `.Values.signing` but not specifying
any of the new private key properties. Tag `v6.0.2` is therefore not following semantic versioning.

This temporarily reverts commit b8f0310c43 and a fix-up commit 57a1cd27d9
to retag 6.0.2 as 6.0.3.

Co-authored-by: justusbunsi <sk.bunsenbrenner@gmail.com>
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/373
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-by: luhahn <luhahn@noreply.gitea.io>

unittests/gpg-secret/signing-enabled.yaml

@@ -1,40 +0,0 @@
-suite: GPG secret template (signing enabled)
-release:
-  name: gitea-unittests
-  namespace: testing
-templates:
-  - templates/gitea/gpg-secret.yaml
-tests:
-  - it: fails rendering when nothing is configured
-    set:
-      signing:
-        enabled: true
-    asserts:
-      - failedTemplate:
-          errorMessage: Either specify `signing.privateKey` or `signing.existingKey`
-  - it: skips rendering using external secret reference
-    set:
-      signing:
-        enabled: true
-        existingSecret: "external-secret-reference"
-    asserts:
-      - hasDocuments:
-          count: 0
-  - it: renders secret specification using inline gpg key
-    set:
-      signing:
-        enabled: true
-        privateKey: "gpg-key-placeholder"
-    asserts:
-      - hasDocuments:
-          count: 1
-      - documentIndex: 0
-        containsDocument:
-          kind: Secret
-          apiVersion: v1
-          name: gitea-unittests-gpg-key
-      - isNotEmpty:
-          path: metadata.labels
-      - equal:
-          path: data.privateKey
-          value: "Z3BnLWtleS1wbGFjZWhvbGRlcg=="