Update github ci to Xcode 13 (beta)

Signed-off-by: Finn Behrens <[email protected]>

Author: kloenk

.github/workflows/ci-build.yml

@@ -17,6 +17,8 @@ jobs:
   build:
     name: Build
     runs-on: macos-latest
+    env:
+        DEVELOPER_DIR: /Applications/Xcode_13.0.app/Contents/Developer
 
     steps:
       - uses: actions/checkout@v2

.github/workflows/ci-tests.yml

@@ -17,6 +17,8 @@ jobs:
   tests:
     name: Tests
     runs-on: macos-latest
+    env:
+        DEVELOPER_DIR: /Applications/Xcode_13.0.app/Contents/Developer
 
     steps:
       - uses: actions/checkout@v2

.github/workflows/release-alpha.yml

@@ -16,6 +16,8 @@ jobs:
   build:
     name: Release
     runs-on: macos-latest
+    env:
+        DEVELOPER_DIR: /Applications/Xcode_13.0.app/Contents/Developer
 
     steps:
       - uses: actions/checkout@v2