fix(packaging): remove excess forward slash in Wix Patch (#18121)

packaging/WixPatch.xml

@@ -1,8 +1,6 @@
 <CPackWiXPatch>
     <!--  Fragment ID is from: <your build dir>/_CPack_Packages/win64/WIX/files.wxs -->
     <CPackWiXFragment Id="CM_CP_bin.nvim.exe">
-      <!-- Note: if we were to specify Value='[INSTALL_ROOT]\bin' - with a backslash, the installer will still
-      use a forward slash in the path. -->
       <Environment
         Id='UpdatePath'
         Name='PATH'
@@ -10,7 +8,7 @@
         Permanent='no'
         System='yes'
         Part='last'
-        Value='[INSTALL_ROOT]/bin'
+        Value='[INSTALL_ROOT]bin'
       />
     </CPackWiXFragment>
 </CPackWiXPatch>