tests: gitlab-cli upgrades packages installed from pip3

.gitlab-ci.yml

@@ -4,7 +4,7 @@ after_script:
 jessie:
   image: adt-jessie_dnspython3_1.11
   before_script:
-    - pip3 install -r tests/requirements.txt
+    - pip3 install --upgrade -r tests/requirements.txt
   script:
     - coverage run --source ./ -m unittest -v tests.test_acme_dns_tiny tests.test_acme_account_rollover tests.test_acme_account_delete
     - coverage report --include=acme_dns_tiny.py,tools/acme_account_rollover.py,tools/acme_account_delete.py
@@ -13,7 +13,7 @@ jessie:
 jessie_backport:
   image: adt-jessie_dnspython3_1.15-bpo
   before_script:
-    - pip3 install -r tests/requirements.txt
+    - pip3 install --upgrade -r tests/requirements.txt
   script:
     - coverage run --source ./ -m unittest -v tests.test_acme_dns_tiny tests.test_acme_account_rollover tests.test_acme_account_delete
     - coverage report --include=acme_dns_tiny.py,tools/acme_account_rollover.py,tools/acme_account_delete.py