add .gyb as an accepted source file (#1191)

* add .gyb to source files

* Update CHANGELOG.md

Co-authored-by: Christian Huck <chris@thinkfield.li>

CHANGELOG.md

@@ -11,6 +11,8 @@
 
 - Added `coverageTargets` for target test schemes. This enables to gather code coverage for specific targets. [#1189](https://github.com/yonaskolb/XcodeGen/pull/1189) @gabriellanata
 
+- Fixed issue where .gyb files could not be added to source file list [#1191]((https://github.com/yonaskolb/XcodeGen/issues/1191) @hakkurishian
+
 ## 2.26.0
 
 ### Added

Sources/ProjectSpec/FileType.swift

@@ -75,6 +75,7 @@ extension FileType {
 
         // sources
         "swift": FileType(buildPhase: .sources),
+        "gyb": FileType(buildPhase: .sources),
         "m": FileType(buildPhase: .sources),
         "mm": FileType(buildPhase: .sources),
         "cpp": FileType(buildPhase: .sources),