Add default needs-triage label to issue templates (#100)

.github/ISSUE_TEMPLATE/BUG_TEMPLATE.md

@@ -2,7 +2,7 @@
 name: 🐛 Bug report
 about: Create a report to help us improve
 title: '[BUG]'
-labels: 'bug, untriaged'
+labels: 'bug, needs-triage
 assignees: ''
 ---
 

.github/ISSUE_TEMPLATE/FEATURE_REQUEST_TEMPLATE.md

@@ -2,7 +2,7 @@
 name: 🎆 Feature request
 about: Request a feature in this project
 title: '[FEATURE]'
-labels: enhancement
+labels: enhancement, needs-triage
 assignees: ''
 ---
 **Is your feature request related to a problem?**

.github/ISSUE_TEMPLATE/PROPOSAL_TEMPLATE.md

@@ -2,7 +2,7 @@
 name: 💭 Proposal
 about: Suggest an idea for a specific feature you wish to propose to the community for comment
 title: '[PROPOSAL]'
-labels: proposal
+labels: proposal, needs-triage
 assignees: ''
 ---
 ## What kind of business use case are you trying to solve? What are your requirements?