Read .gr file, convert to utf-8:

src/diffpy/srmise/pdfdataset.py

@@ -202,7 +202,10 @@ def read(self, filename):
         self
         """
         try:
-            self.readStr(open(filename, "rb").read())
+            # Open the file in binary mode, read it, and decode to convert bytes to string
+            with open(filename, "rb") as file:
+                file_content = file.read().decode('utf-8')
+            self.readStr(file_content)
         except PDFDataFormatError as err:
             basename = os.path.basename(filename)
             emsg = ("Could not open '%s' due to unsupported file format " + "or corrupted data. [%s]") % (