update get_version_from_git.sh script

Author: Stefano Torresi

.ci/get_version_from_git.sh

@@ -1,8 +1,12 @@
 #!/bin/sh
-TAG=$(git tag | grep -E "[0-9]\.[0-9]\.[0-9]" | sort -rn | head -n1)
+
+# https://semver.org/#is-there-a-suggested-regular-expression-regex-to-check-a-semver-string
+SEMVER_REGEX="^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$"
+
+TAG=$(git tag | grep -P "$SEMVER_REGEX" | sed '/-/!{s/$/_/}' | sort -V | sed 's/_$//' | tail -n1)
 
 if [ -z "${TAG}" ]; then
-	echo "Could not find any tag" 1>&2
+	echo "Could not find any semver tag" 1>&2
 	exit 1
 else
 	COMMITS_SINCE_TAG=$(git rev-list "${TAG}".. --count)