pack subcommand cannot find microchip samd51 DFP

HI, thank you very much of this great project. I would like to report an issue where the pack command couldn't find the SAMD51 target although it is listed in the offical pack https://www.keil.com/dd2/pack/ .

$ pyocd --version
0.28.0
$ pyocd pack -f samd5
0000306:WARNING:__main__:No matching devices. Please make sure the pack index is up to date.

My PC is running ubuntu 20.04 with python3. I did notice there is a list of ERRO and WARN when running pack update though.

$ pyocd pack -u
0000310:INFO:__main__:Updating pack index...
Sep 30 00:51:32.779 ERRO download of "https://www.keil.com/pack/Keil.STM32H7xx_DFP.pdsc" failed: https://www.keil.com/pack/Keil.STM32H7xx_DFP.pdsc: error trying to connect: unexpected end of file
Sep 30 00:51:33.113 WARN tried to parse element "package" from element "html"
Sep 30 00:51:33.113 WARN tried to parse element "package" from element "html"
Sep 30 00:51:33.158 WARN error while parsing attribute at position 13: Attribute value must start with a quote
Sep 30 00:51:33.195 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.198 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.202 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.204 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.230 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.230 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.230 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.230 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.230 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.233 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.243 WARN tried to parse element "package" from element "head"
Sep 30 00:51:33.243 WARN tried to parse element "package" from element "head"
Sep 30 00:51:33.245 WARN Only Comment, CDATA and DOCTYPE nodes can start with a '!'
Sep 30 00:51:33.255 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.256 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.256 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.287 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.287 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.288 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.288 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.288 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.288 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.288 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.300 WARN invalid digit found in string, Package: TLE984x_DFP, Vendor: Infineon
Sep 30 00:51:33.314 WARN Only Comment, CDATA and DOCTYPE nodes can start with a '!'
Sep 30 00:51:33.319 WARN the XML is invalid, an element was wrongly closed
Sep 30 00:51:33.344 WARN Unknown file catogory preIncludeLocal, Group: Unity, Class: Test, in: Component, Package: Unity, Vendor: Arm-Packs
Sep 30 00:51:33.379 WARN No Core found!, Package: CMSIS, Vendor: ARM

Start with the pyocd pack -u and pyocd pack -f samd5 entry points, reproducing the failed pack-index download and the missing SAMD51 match. Trace pack index parsing and device filtering, then verify that updating the index handles the reported response errors and that the SAMD51 target is found by the filter.