[lint.ps1] Ignore PSAvoidUsingPositionalParameters

I do not understand why this linter has started complaining now, as we
use positional parameters in many functions:

```
packages\common.vm\tools\vm.common\vm.common.psm1
1 rule violation found.    Severity distribution:  Error = 0, Warning = 0, Information = 1

RuleName                            Severity     ScriptName Line  Message
--------                            --------     ---------- ----  -------
PSAvoidUsingPositionalParameters    Information  vm.common. 393   Cmdlet 'VM-Install-From-Zip' has positional
                                                 psm1             parameter. Please use named parameters instead of
                                                                  positional parameters when calling a command.
```

Exclude this violation as it is of `Information` severity and we would
need to make a lot of changes to fix it.

scripts/test/lint.ps1

@@ -1,6 +1,6 @@
 # PSUseApprovedVerbs is disabled to support VM- functions
 # TODO: Enable other rules
-$excludedRules = "PSAvoidUsingInvokeExpression", "PSUseApprovedVerbs", "PSAvoidUsingWriteHost", "PSUseShouldProcessForStateChangingFunctions", "PSUseSingularNouns"
+$excludedRules = "PSAvoidUsingInvokeExpression", "PSUseApprovedVerbs", "PSAvoidUsingWriteHost", "PSUseShouldProcessForStateChangingFunctions", "PSUseSingularNouns", "PSAvoidUsingPositionalParameters"
 
 choco install psscriptanalyzer --version 1.20.0 --no-progress