Implemented some tests for the RunProcessTaskTests case tests in the tests target.

Library/Sources/Internal/Tasks/RunProcessTask.swift

@@ -60,7 +60,7 @@ struct RunProcessTask {
         } catch let error as RunProcessError {
             throw error
         } catch {
-            throw RunProcessError.captured(error)
+            throw RunProcessError.captured(error.localizedDescription)
         }
     }
     
@@ -68,8 +68,8 @@ struct RunProcessTask {
 
 // MARK: - Errors
 
-public enum RunProcessError: Error {
-    case captured(_ error: Error)
+public enum RunProcessError: Error, Equatable {
+    case captured(_ output: String)
     case output(_ output: String)
     case unexpected
 }