Allow range requests for a single byte (#2851)

Co-authored-by: L. Karkkainen <tronic@users.noreply.github.com>
Co-authored-by: Adam Hopkins <adam@amhopkins.com>

sanic/handlers/content_range.py

@@ -62,7 +62,7 @@ def __init__(self, request: Request, stats: os.stat_result) -> None:
                 # this case represents `Content-Range: bytes -5`
                 self.start = self.total - self.end
                 self.end = self.total - 1
-        if self.start >= self.end:
+        if self.start > self.end:
             raise RangeNotSatisfiable(
                 "Invalid for Content Range parameters", self
             )