.gitlab: Add template for Security Report

This should help us to have minimally useful reports about security.

.gitlab/issue_templates/Default.md

@@ -1,6 +1,6 @@
 <!-- ⚠️ IMPORTANT: READ ME! ⚠️
 This is the default template for bug reports.
-For feature requests or performance issues, please switch instead to the appropriate template in the "Choose a template" list.
+For feature requests, performance issues and security reports, please switch instead to the appropriate template in the "Choose a template" list.
 
 It is important that you fill all the fields of the template.
 

.gitlab/issue_templates/security.md

@@ -0,0 +1,30 @@
+<!-- ⚠️ IMPORTANT: READ ME! ⚠️
+This is the template for security reports.
+For bug reports, feature requests and performance issues, please switch instead to the appropriate template in the "Choose a template" list.
+
+It is important that you fill all the fields of the template. -->
+
+### Environment/Versions
+
+- GIMP version number:
+- Package: <!--[flatpak? Installer from gimp.org? If another installer, tell us where from] (write it after the > symbol)-->
+- Operating System: <!--[Windows? macOS? Linux? All?] (write it after the > symbol) -->
+
+<!-- Note: security reporters are expected to have verified the bug still exists
+either in the last stable version of GIMP or on updated development code
+(master branch). -->
+
+### Security Report Description
+
+<!-- Please provide a general description of the security issue (with CVE code if possible). -->
+
+### Antivirus Log
+
+<!-- Please attach a antivirus log or other file detailing the issue, and attach it to the report.
+If you have none, at least report GIMP as false positive to the antivirus before continuing. -->
+
+### Additional information
+
+<!-- If there you know the culprit code, please link it here. -->
+
+/label ~"1. Security"