Update dependencies from https://github.com/dotnet/arcade build 779 (#169)

This change updates the following dependencies
- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.18613.20

eng/Version.Details.xml

@@ -2,9 +2,9 @@
 <Dependencies>
   <ProductDependencies></ProductDependencies>
   <ToolsetDependencies>
-    <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="1.0.0-beta.18612.12">
+    <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="1.0.0-beta.18613.20">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>ffc7a871add67b229c7fd41ad1cdff41da926312</Sha>
+      <Sha>76eb87c3f3de6954a2523490688e3a93e1763256</Sha>
     </Dependency>
   </ToolsetDependencies>
 </Dependencies>

eng/common/templates/job/job.yml

@@ -95,11 +95,26 @@ jobs:
 
   variables:
   - ${{ each variable in parameters.variables }}:
+    # handle name-value variable syntax
+    # example:
+    # - name: [key]
+    #   value: [value]
     - ${{ if ne(variable.name, '') }}:
       - name: ${{ variable.name }}
         value: ${{ variable.value }}
+    
+    # handle variable groups
     - ${{ if ne(variable.group, '') }}:
       - group: ${{ variable.group }}
+
+    # handle key-value variable syntax.
+    # example:
+    # - [key]: [value]
+    - ${{ if and(eq(variable.name, ''), eq(variable.group, '')) }}:
+      - ${{ each pair in variable }}:
+        - name: ${{ pair.key }}
+          value: ${{ pair.value }}
+
   # Add additional variables
   - ${{ if and(ne(parameters.helixRepo, ''), eq(parameters.runAsPublic, 'false'), ne(variables['System.TeamProject'], 'public'), notIn(variables['Build.Reason'], 'PullRequest')) }}:
     - name: _HelixSource

global.json

@@ -9,6 +9,6 @@
     "version": "3.0.100-preview-009764"
   },
   "msbuild-sdks": {
-    "Microsoft.DotNet.Arcade.Sdk": "1.0.0-beta.18612.12"
+    "Microsoft.DotNet.Arcade.Sdk": "1.0.0-beta.18613.20"
   }
 }