parser.py: nicer plurals

Deal with plural in a better way, in a couple of additional non-debug
places. While at it, update the README.
Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com>

README.md

@@ -36,8 +36,8 @@ command. The parsed report can be found in `result.md`.
 $ ./parser.py \
                 </path/to/sct_results/Overall/Summary.ekl> \
 		contrib/v21.07_0.9_BETA/EBBR.seq
-INFO apply_rules: Updated 200 test(s) out of 12206 after applying 124 rule(s)
-INFO main: 0 dropped(s), 1 failure(s), 93 ignored(s), 106 known u-boot limitation(s), 12006 pass(s), 0 warning(s)
+INFO apply_rules: Updated 200 tests out of 12206 after applying 124 rules
+INFO main: 0 dropped, 1 failure, 93 ignored, 106 known u-boot limitations, 12006 pass, 0 warning
 ```
 
 (The `EBBR.yaml' configuration file is used to process results by default.)

parser.py

@@ -353,7 +353,8 @@ def apply_rules(cross_check, conf):
     if n:
         r = len(conf)
         logging.info(
-            f'Updated {n} test(s) out of {s} after applying {r} rule(s)')
+            f"Updated {n} {maybe_plural(n, 'test')} out of {s}"
+            f" after applying {r} {maybe_plural(r, 'rule')}")
 
 
 # Use YAML configuration file and perform all the transformations described in
@@ -388,7 +389,8 @@ def filter_data(cross_check, Filter):
 
     r = list(filter(function, cross_check))
     after = len(r)
-    logging.info(f"Filtered out {before - after} test(s), kept {after}")
+    n = before - after
+    logging.info(f"Filtered out {n} {maybe_plural(n, 'test')}, kept {after}")
     return r