Update .gitignore with pytest files

When running tests, multiple files are generated,
ending up in the tracked files, making development
and use of advanced editors hard. This changes untrack
all produced files, so that when running `git diff` the
status is clean.

Author: bastonero

.gitignore

@@ -50,6 +50,20 @@ coverage.xml
 *.cover
 .hypothesis/
 .pytest_cache
+input_tmp.in
+tmp_dyn*
+dyn_end_*
+dyn_start_*
+final_dyn*
+grad_*.dat
+u_population*.dat
+energies*.dat
+forces_*.dat
+prova
+scf_population*.dat
+frequencies*.*
+timer.json
+minim.dat
 
 # Translations
 *.mo