Fix build issues (#980)

Technical
- Fix duplicate assembly reference build warnings
- Fix issue where release version number generated on pull request

.config/dotnet-tools.json

@@ -15,7 +15,7 @@
       ]
     },
     "ghul.compiler": {
-      "version": "0.5.12",
+      "version": "0.5.15",
       "commands": [
         "ghul-compiler"
       ]

.github/workflows/ci.yml

@@ -36,6 +36,8 @@ jobs:
       uses: degory/create-version@v0.0.2
       with:
         token: ${{ secrets.GITHUB_TOKEN }}
+      env:
+        PRERELEASE: ${{ github.event_name == 'pull_request' }}
 
   unit_tests:
     name: Run unit tests

ghul.ghulproj

@@ -45,10 +45,6 @@
     <GhulOptions Include="--define release" Condition="'$(CI)' != ''" />
 
     <!-- Package dependencies -->
-    <PackageReference Include="ghul.targets" />
-    <PackageReference Include="ghul.runtime" />
-    <PackageReference Include="ghul.pipes" />
-
     <PackageReference Include="System.Reflection.MetadataLoadContext" Version="6.0.0" />
     <PackageReference Include="runtime.linux-x64.Microsoft.NETCore.ILAsm" Version="6.0.0" />
     <PackageReference Include="runtime.win-x64.Microsoft.NETCore.ILAsm" Version="6.0.0" />