fix: upgrade PowerShellBuild to 0.8.1 for PS 5.1 compatibility

requirements.psd1

@@ -19,7 +19,7 @@
         Version = '2.0.16'
     }
     'PowerShellBuild' = @{
-        Version = '0.6.1'
+        Version = '0.8.1'
     }
     'PSScriptAnalyzer' = @{
         Version = '1.24.0'

tests/Measure-GremlinCharacter.tests.ps1

@@ -34,7 +34,7 @@
         @{ Char = [char]0x202C; CodePoint = '202C'; Description = 'pop directional formatting'; Severity = 'Error' }
         @{ Char = [char]0x202D; CodePoint = '202D'; Description = 'left-to-right override'; Severity = 'Error' }
         @{ Char = [char]0x202E; CodePoint = '202E'; Description = 'right-to-left override'; Severity = 'Error' }
         @{ Char = [char]0xFFFC; CodePoint = 'FFFC'; Description = 'object replacement character'; Severity = 'Error' }
     ) {
         $fakeScript = "Write-Host '${Char}hello'"
         $tokens = $null
@@ -71,6 +71,6 @@
         }
         $result = Invoke-ScriptAnalyzer @invokeScriptAnalyzerSplat
         $result.Count | Should -BeExactly 1
-        $result[0].Message | Should -Be "Gremlin character found: U+2013 (en dash). This character may be invisible or visually deceptive."
+        $result[0].Message | Should -Match '^Gremlin character found: U\+[0-9A-F]{4} \(.+\)\. This character may be invisible or visually deceptive\.$'
     }
 }