Added upper bound for VS versions.

Author: camrein

src/ParallelHelper.Plugin/source.extension.vsixmanifest

@@ -11,22 +11,22 @@
         <Tags>C#; Parallel; Asynchronous; Concurrency; Bugs; Best Practices; TPL; Task; QC; Static Analysis; async; await</Tags>
     </Metadata>
     <Installation>
-        <InstallationTarget Id="Microsoft.VisualStudio.Community" Version="[16.3,)">
+        <InstallationTarget Id="Microsoft.VisualStudio.Community" Version="[16.3,17.0)">
             <ProductArchitecture>x86</ProductArchitecture>
         </InstallationTarget>
-        <InstallationTarget Id="Microsoft.VisualStudio.Community" Version="[17.0,)">
+        <InstallationTarget Id="Microsoft.VisualStudio.Community" Version="[17.0,18.0)">
             <ProductArchitecture>amd64</ProductArchitecture>
         </InstallationTarget>
-        <InstallationTarget Id="Microsoft.VisualStudio.Pro" Version="[16.3,)">
+        <InstallationTarget Id="Microsoft.VisualStudio.Pro" Version="[16.3,17.0)">
             <ProductArchitecture>x86</ProductArchitecture>
         </InstallationTarget>
-        <InstallationTarget Id="Microsoft.VisualStudio.Pro" Version="[17.0,)">
+        <InstallationTarget Id="Microsoft.VisualStudio.Pro" Version="[17.0,18.0)">
             <ProductArchitecture>amd64</ProductArchitecture>
         </InstallationTarget>
-        <InstallationTarget Id="Microsoft.VisualStudio.Enterprise" Version="[16.3,)">
+        <InstallationTarget Id="Microsoft.VisualStudio.Enterprise" Version="[16.3,17.0)">
             <ProductArchitecture>x86</ProductArchitecture>
         </InstallationTarget>
-        <InstallationTarget Id="Microsoft.VisualStudio.Enterprise" Version="[17.0,)">
+        <InstallationTarget Id="Microsoft.VisualStudio.Enterprise" Version="[17.0,18.0)">
             <ProductArchitecture>amd64</ProductArchitecture>
         </InstallationTarget>
     </Installation>