tests: successfully validate rc versions

For testing versions the version string differs for git tag (v2.22.0-rc3)
and tarball file name (2.22.0.rc3). Let's fix validation for testing
versions.

Signed-off-by: Christian Hesse <mail@eworm.de>

tests/t0001-validate-git-versions.sh

@@ -33,7 +33,7 @@ test_expect_success 'test submodule version matches Makefile' '
 				sed -e "s/^[0-9]* \\([0-9a-f]*\\) [0-9]	.*$/\\1/") &&
 			cd git &&
 			git describe --match "v[0-9]*" $sm_sha1
-		) | sed -e "s/^v//" >sm_version &&
+		) | sed -e "s/^v//" -e "s/-/./" >sm_version &&
 		test_cmp sm_version makefile_version
 	fi
 '