[ci] Enable pep8speaks for code style checking in the repository

.pep8speaks.yml

@@ -0,0 +1,22 @@
+message:
+    opened:
+        header: "Hello @{name}, Thank you for submitting the Pull Request!"
+        footer: "Do see the ReFrame [Coding Style Guide](https://github.com/eth-cscs/reframe/wiki/coding-style-guide)"
+    updated:
+        header: "Hello @{name}, Thank you for updating!"
+        footer: "Do see the ReFrame [Coding Style Guide](https://github.com/eth-cscs/reframe/wiki/coding-style-guide)"
+    no_errors: "Cheers! There are no PEP8 issues in this Pull Request!"
+
+only_mention_files_with_errors: True
+
+scanner:
+    diff_only: True
+
+pycodestyle:
+    max-line-length: 79
+    ignore:
+        - E129
+        - E221
+        - E226
+        - E241
+        - E272

reframe/core/schedulers/slurm.py

@@ -44,7 +44,7 @@ class SlurmJob(sched.Job):
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
-        self._prefix  = '#SBATCH'
+        self._prefix = '#SBATCH'
         self._completion_states = [SLURM_JOB_BOOT_FAIL,
                                    SLURM_JOB_CANCELLED,
                                    SLURM_JOB_COMPLETED,