[TECO-6] <enhance> change fixed version string to placeholder.

snap/snapcraft.yaml

 name: tdengine
-base: core18 # the base snap is the execution environment for this snap
-version: '2.0.2.0' # just for humans, typically '1.2+git' or '1.3.2'
+base: core18
+version: 'RELEASE_VERSION'
 icon: snap/gui/t-dengine.svg
 summary: an open-source big data platform designed and optimized for IoT. 
 description: |
@@ -72,7 +72,7 @@ parts:
       - usr/bin/taosd
       - usr/bin/taos
       - usr/bin/taosdemo
-      - usr/lib/libtaos.so.2.0.2.0
+      - usr/lib/libtaos.so.RELEASE_VERSION
       - usr/lib/libtaos.so.1
       - usr/lib/libtaos.so