Add PklProject.deps.json file with newline for POSIX compliance (#664)

* Add Project.deps.json file with newline for POSIX compliance

* Fix test cases

pkl-core/src/main/java/org/pkl/core/project/ProjectDeps.java

@@ -218,6 +218,7 @@ public final class ProjectDeps {
       }
       jsonWriter.endObject();
       jsonWriter.endObject();
+      jsonWriter.newline();
       jsonWriter.close();
     }
   }

pkl-core/src/test/files/LanguageSnippetTests/input/projects/project6/PklProject.deps.json

@@ -1,4 +1,4 @@
 {
   "schemaVersion": 1,
   "resolvedDependencies": {}
-}
+}

pkl-core/src/test/kotlin/org/pkl/core/project/ProjectDependenciesResolverTest.kt

@@ -86,6 +86,7 @@ class ProjectDependenciesResolverTest {
           }
         }
       }
+      
     """
           .trimIndent()
       )

pkl-core/src/test/kotlin/org/pkl/core/project/ProjectDepsTest.kt

@@ -44,6 +44,7 @@ class ProjectDepsTest {
             }
           }
         }
+        
       """
       .trimIndent()