Update appveyor.yml

Author: SlavaRa

appveyor.yml

@@ -35,7 +35,9 @@ after_build:
 - cd %PLUGIN_PATH%
 - md5sum %APPVEYOR_BUILD_FOLDER%\%PLUGIN_NAME%.fdz > checksum.md5
 - cat checksum.md5
-- sed -e "s/^\\|\s.*//" checksum.md5 > checksum.tmp.md5 && mv checksum.tmp.md5 checksum.md5
+- sed -e "s/\s.*//" checksum.md5 > checksum.tmp.md5
+- sed -e "s/^\\//" checksum.tmp.md5 > checksum.md5
+- cat checksum.md5
 - set /p CHECKSUM=<checksum.md5
 - echo %CHECKSUM%
 - mv %APPMAN_TEMPLATE% %APPMAN_CONFIG_XML%