clang-format: update latest spec and reformat with clang-20

Copy the latest format file from the docs repository and apply using
clang-format-20.

See I1818407fdd8ab2ca11a939ffebd5f3e5445403c3 for clang-20 enablement.

A further consequence of clang-20 was a new tidy warning from the tests:

```
../tests/dsp/firmware_update.cpp:2842:63: error: both sides of operator are equivalent [misc-redundant-expression,-warnings-as-errors]
 2842 |     maxOutstandingTransferReq = PLDM_FWUP_MIN_OUTSTANDING_REQ - 1;
```

Set the value directly to zero instead.

Change-Id: I01426569c63bc2663984c860178648be6fb423e0
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/tests/dsp/firmware_update.cpp b/tests/dsp/firmware_update.cpp
index ebf6495..01ea091 100644
--- a/tests/dsp/firmware_update.cpp
+++ b/tests/dsp/firmware_update.cpp
@@ -2839,7 +2839,7 @@
     EXPECT_EQ(rc, PLDM_ERROR_INVALID_DATA);
     maxTransferSize = PLDM_FWUP_BASELINE_TRANSFER_SIZE;
 
-    maxOutstandingTransferReq = PLDM_FWUP_MIN_OUTSTANDING_REQ - 1;
+    maxOutstandingTransferReq = 0;
     rc = encode_request_update_req(
         instanceId, maxTransferSize, numOfComp, maxOutstandingTransferReq,
         pkgDataLen, PLDM_STR_TYPE_ASCII, compImgSetVerStrLen,