Make SDK manager checker happy

When we upgraded to platform-tools 31.0.3, we missed updating
package.xml, so SDK manager was thinking we were on an old version.

Dowloading 31.0.3 through SDK manager only updates package.xml

Test: studio SDK manager no longer warns
Change-Id: I2b37a0b9aa1d3a0f78118471f4d01642b0388549
1 file changed