docs(issue templates): use issue types (#1533)

.github/ISSUE_TEMPLATE/bug_report.md

@@ -2,7 +2,7 @@
 name: Bug report
 about: Topgrade is misbehaving
 title: ''
-labels: 'C-bug'
+type: Bug
 assignees: ''
 
 ---

.github/ISSUE_TEMPLATE/feature_request.md

@@ -2,7 +2,7 @@
 name: General feature request
 about: Suggest a general feature, or feature within an already existing step
 title: ''
-labels: C-feature request
+type: Feature
 assignees: ''
 
 ---

.github/ISSUE_TEMPLATE/step_request.md

@@ -2,7 +2,8 @@
 name: New step request
 about: Suggest a new step/package manager to update
 title: ''
-labels: C-feature request, request step
+type: Feature
+labels: request step
 assignees: ''
 
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