fix: add lost code back in (#254)

this PR compensates for gpu support lost between 1.1 und 1.2

Furthermore some account handling issues has been corrected: If no
account is specified, it can be 'none'. This is no Python type and
always the root of the SLURM account tree. Instead, upon checking 'None'
is returned.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- **Improved job submission:** The scheduling system now detects GPU
usage to dynamically allocate tasks with optimal settings, ensuring more
precise and efficient job execution.
- **Enhanced account retrieval:** The process has been updated to
correctly handle scenarios where account details aren’t needed,
improving compatibility across diverse cluster environments.
- Overall, these updates align with current scheduling standards,
resulting in a more reliable user experience.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: cmeesters

snakemake_executor_plugin_slurm/__init__.py

@@ -261,6 +261,13 @@ def run_job(self, job: JobExecutorInterface):
                 "- submitting without. This might or might not work on your cluster."
             )
 
+            # fixes #40 - set ntasks regardless of mpi, because
+            # SLURM v22.05 introduced the requirement for all jobs
+            gpu_job = job.resources.get("gpu") or "gpu" in job.resources.get("gres", "")
+            if gpu_job:
+                call += f" --ntasks-per-gpu={job.resources.get('tasks', 1)}"
+            else:
+                call += f" --ntasks={job.resources.get('tasks', 1)}"
         # MPI job
         if job.resources.get("mpi", False):
             if not job.resources.get("tasks_per_node") and not job.resources.get(
@@ -627,12 +634,14 @@ def get_account(self):
         tries to deduce the acccount from recent jobs,
         returns None, if none is found
         """
-        cmd = f'sacct -nu "{os.environ["USER"]}" -o Account%256 | head -n1'
+        cmd = f'sacct -nu "{os.environ["USER"]}" -o Account%256 | tail -1'
         try:
             sacct_out = subprocess.check_output(
                 cmd, shell=True, text=True, stderr=subprocess.PIPE
             )
-            return sacct_out.replace("(null)", "").strip()
+            possible_account = sacct_out.replace("(null)", "").strip()
+            if possible_account == "none":  # some clusters may not use an account
+                return None
         except subprocess.CalledProcessError as e:
             self.logger.warning(
                 f"No account was given, not able to get a SLURM account via sacct: "