build(python): drop support for Python 3.6 and 3.7 (#715)

BREAKING CHANGE: drop support for Python 3.6 and 3.7

Closes reanahub/reana#784

.github/workflows/ci.yml

@@ -189,14 +189,14 @@ jobs:
     strategy:
       matrix:
         testenv: [lowest, release]
-        python: ['3.6', '3.7', '3.8', '3.9', '3.10', '3.11', '3.12']
+        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
     steps:
       - uses: actions/checkout@v4
 
       - name: Set up Python ${{ matrix.python }}
         uses: actions/setup-python@v5
         with:
-          python-version: ${{ matrix.python }}
+          python-version: ${{ matrix.python-version }}
 
       - name: Setup requirements builder
         run: |

reana_client/utils.py

@@ -139,22 +139,18 @@ def get_workflow_duration(workflow: Dict) -> Optional[int]:
         time is not present.
     """
 
-    # FIXME: Use datetime.fromisoformat when moving to Python 3.7 or higher
-    def fromisoformat(date_string):
-        return datetime.strptime(date_string, "%Y-%m-%dT%H:%M:%S")
-
     progress = workflow.get("progress", {})
     run_started_at = progress.get("run_started_at")
     run_finished_at = progress.get("run_finished_at")
     run_stopped_at = progress.get("run_stopped_at")
 
     duration = None
     if run_started_at:
-        start_time = fromisoformat(run_started_at)
+        start_time = datetime.fromisoformat(run_started_at)
         if run_finished_at:
-            end_time = fromisoformat(run_finished_at)
+            end_time = datetime.fromisoformat(run_finished_at)
         elif run_stopped_at:
-            end_time = fromisoformat(run_stopped_at)
+            end_time = datetime.fromisoformat(run_stopped_at)
         else:
             end_time = datetime.utcnow()
         duration = round((end_time - start_time).total_seconds())

setup.py

@@ -50,7 +50,6 @@
     "tablib>=0.12.1,<0.13",
     "werkzeug>=0.14.1 ; python_version<'3.10'",
     "werkzeug>=0.15.0 ; python_version>='3.10'",
-    "swagger_spec_validator>=2.4.0,<3.0.0; python_version<'3.7'",
 ]
 
 packages = find_packages()
@@ -82,7 +81,7 @@
             "reana-cwl-runner = reana_client.cli.cwl_runner:cwl_runner",
         ],
     },
-    python_requires=">=3.6",
+    python_requires=">=3.8",
     extras_require=extras_require,
     install_requires=install_requires,
     setup_requires=setup_requires,
@@ -94,8 +93,6 @@
         "License :: OSI Approved :: MIT License",
         "Operating System :: OS Independent",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.6",
-        "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",