Add the ability to run upgrade test (#21)

Upgrade test runs after regression test. It is need to generate tar-archive with previous
versions of diskquota. Path to archive is set in command to run Docker:
"<PATH_TO_ARCHIVE_WITH_OLD_VERSIONS>".

Before run tests it is needed to run build step:
```
docker run --rm -it -e DISKQUOTA_OS=rhel7 \
       -v /tmp/diskquota_artifacts:/home/gpadmin/diskquota_artifacts \
       -v <PATH_TO_DISKQUOTA_SRC>:/home/gpadmin/diskquota_src \
       -v <PATH_TO_CMAKE_INSTALL_SCRIPT>:/home/gpadmin/bin_cmake/cmake-3.20.0-linux-x86_64.sh \
       hub.adsw.io/library/gpdb6_regress:latest diskquota_src/concourse/scripts/entry.sh build
```

Full command to run all tests in Docker:
```
docker run --rm -it --sysctl 'kernel.sem=500 1024000 200 4096' \
       -v /tmp/diskquota_artifacts:/home/gpadmin/bin_diskquota \
       -v <PATH_TO_DISKQUOTA_SRC>:/home/gpadmin/diskquota_src \
       -v <PATH_TO_CMAKE_INSTALL_SCRIPT>:/home/gpadmin/bin_cmake/cmake-3.20.0-linux-x86_64.sh \
       -v <PATH_TO_ARCHIVE_WITH_OLD_VERSIONS>:/home/gpadmin/diskquota_old_versions.tar \
       hub.adsw.io/library/gpdb6_regress:latest diskquota_src/concourse/scripts/entry.sh test
```

arenadata/README.md

@@ -24,6 +24,6 @@ docker run --rm -it --sysctl 'kernel.sem=500 1024000 200 4096' \
        -v /tmp/diskquota_artifacts:/home/gpadmin/bin_diskquota \
        -v <PATH_TO_DISKQUOTA_SRC>:/home/gpadmin/diskquota_src \
        -v <PATH_TO_CMAKE_INSTALL_SCRIPT>:/home/gpadmin/bin_cmake/cmake-3.20.0-linux-x86_64.sh \
-       -v <PATH_TO_ARCHIVE_WITH_OLD_VERSIONS>://home/gpadmin/diskquota_old_versions.tar \
+       -v <PATH_TO_ARCHIVE_WITH_OLD_VERSIONS>:/home/gpadmin/diskquota_old_versions.tar \
        hub.adsw.io/library/gpdb6_regress:latest diskquota_src/concourse/scripts/entry.sh test
 ```

src/diskquota.c

@@ -382,7 +382,7 @@ disk_quota_worker_main(Datum main_arg)
 		int major = -1, minor = -1;
 		int has_error = worker_spi_get_extension_version(&major, &minor) != 0;
 
-		if (major == DISKQUOTA_MAJOR_VERSION) break;
+		if (major == DISKQUOTA_MAJOR_VERSION && minor == DISKQUOTA_MINOR_VERSION) break;
 #if GP_VERSION_NUM < 70000
 		/* MemoryAccount has been removed on gpdb7 */
 		MemoryAccounting_Reset();