fix: src/emailservice/Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN12-GLIBC-5927132
- https://snyk.io/vuln/SNYK-DEBIAN12-GLIBC-5927132
- https://snyk.io/vuln/SNYK-DEBIAN12-GLIBC-6210098
- https://snyk.io/vuln/SNYK-DEBIAN12-GLIBC-6210098
- https://snyk.io/vuln/SNYK-DEBIAN12-KRB5-7411315

src/emailservice/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM python:3.7-slim as base
+FROM python:3.13.0rc1-slim as base
 
 FROM base as builder