GatewayDescriptor parsing independent of DIB order

[farmio]

Description

Fix GatewayDescriptor parsing when SearchResponseExtended DIBs are in unexpected order

When DIBSecuredServiceFamilies was parsed after DIBSuppSVCFamilies it overwrote its previously parsed fields because the isinstance() check matched as one derived from the other.

Fixes # (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• The documentation has been adjusted accordingly
• Tests have been added that prove the fix is effective or that the feature works
• The changes are documented in the changelog (docs/changelog.md)

[codecov]

Codecov Report

Merging #981 (8824563) into main (30edee5) will increase coverage by 0.10%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #981      +/-   ##
==========================================
+ Coverage   96.00%   96.11%   +0.10%     
==========================================
  Files         131      131              
  Lines        7942     7948       +6     
==========================================
+ Hits         7625     7639      +14     
+ Misses        317      309       -8     

Impacted Files	Coverage Δ
xknx/knxip/dib.py	89.82% <100.00%> (+1.00%)	⬆️
xknx/io/gateway_scanner.py	97.77% <0.00%> (+5.18%)	⬆️