fix: type backward compatibility (#578)

.changeset/slimy-bags-hope.md

packages/core/package.json

packages/core/src/readers/CSVReader.ts

packages/core/src/readers/DocxReader.ts

packages/core/src/readers/HTMLReader.ts

packages/core/src/readers/ImageReader.ts

packages/core/src/readers/LlamaParseReader.ts

packages/core/src/readers/MarkdownReader.ts

packages/core/src/readers/PDFReader.ts

packages/core/src/readers/SimpleDirectoryReader.ts

packages/core/src/readers/type.ts

packages/core/src/storage/FileSystem.ts

packages/core/src/storage/StorageContext.ts

packages/core/src/storage/docStore/SimpleDocumentStore.ts

packages/core/src/storage/docStore/types.ts

packages/core/src/storage/indexStore/SimpleIndexStore.ts

packages/core/src/storage/indexStore/types.ts

packages/core/src/storage/kvStore/SimpleKVStore.ts

packages/core/src/storage/kvStore/types.ts

packages/core/src/storage/vectorStore/PGVectorStore.ts