packer: remove duplicate version variable

When listing installed plugins, we check that the plugin's reported
version through describe matches what's in the name of the file.

Doing do, we were parsing the same version string twice without
modifying it, which was not necessary, so this commit changes that.

packer/plugin-getter/plugins.go

@@ -191,19 +191,13 @@ func (pr Requirement) ListInstallations(opts ListInstallationsOptions) (InstallL
 			continue
 		}
 
-		rawVersion, err := goversion.NewVersion(pluginVersionStr)
-		if err != nil {
-			log.Printf("malformed version string in filename %q: %s, ignoring", pluginVersionStr, err)
-			continue
-		}
-
 		descVersion, err := goversion.NewVersion(describeInfo.Version)
 		if err != nil {
 			log.Printf("malformed reported version string %q: %s, ignoring", describeInfo.Version, err)
 			continue
 		}
 
-		if rawVersion.Compare(descVersion) != 0 {
+		if ver.Compare(descVersion) != 0 {
 			log.Printf("plugin %q reported version %q while its name implies version %q, ignoring", path, describeInfo.Version, pluginVersionStr)
 			continue
 		}
@@ -225,7 +219,7 @@ func (pr Requirement) ListInstallations(opts ListInstallationsOptions) (InstallL
 		// Note: we use the raw version name here, without the pre-release
 		// suffix, as otherwise constraints reject them, which is not
 		// what we want by default.
-		if !pr.VersionConstraints.Check(rawVersion.Core()) {
+		if !pr.VersionConstraints.Check(ver.Core()) {
 			log.Printf("[TRACE] version %q of file %q does not match constraint %q", pluginVersionStr, path, pr.VersionConstraints.String())
 			continue
 		}