run jlink with default shell on each OS

(bash on mac causes problems with variable substitution)

.github/workflows/build.yml

@@ -6,10 +6,6 @@ on:
 env:
   JAVA_VERSION: 16
 
-defaults:
-  run:
-    shell: bash
-
 jobs: 
   test:
     name: Build and Test
@@ -59,6 +55,9 @@ jobs:
         - os: macOS-latest
           profile: mac
           launcher: launcher-mac.sh
+    defaults:
+      run:
+        shell: bash
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-java@v1