Updated ProjectListItem.jsx to accept GCP files

I have updated the accepted file type to include .txt files so that the
gcp_list.txt files can be accepted.

app/static/app/js/components/ProjectListItem.jsx

@@ -95,7 +95,7 @@ class ProjectListItem extends React.Component {
         url : `/api/projects/${this.state.data.id}/tasks/`,
         parallelUploads: 9999999,
         uploadMultiple: true,
-        acceptedFiles: "image/*",
+        acceptedFiles: "image/*, .txt",
         autoProcessQueue: true,
         createImageThumbnails: false,
         clickable: this.uploadButton,