fix block regular expression

Author: tsaihsiaoyi

fortls/regex_patterns.py

@@ -40,7 +40,7 @@ class FortranRegularExpressions:
     SUBMOD: Pattern = compile(r"[ ]*SUBMODULE[ ]*\(", I)
     END_SMOD: Pattern = compile(r"SUBMODULE", I)
     END_PRO: Pattern = compile(r"(MODULE)?[ ]*PROCEDURE", I)
-    BLOCK: Pattern = compile(r"[ ]*([a-z_]\w*[ ]*:[ ]*)?BLOCK|CRITICAL(?!\w)", I)
+    BLOCK: Pattern = compile(r"[ ]*([a-z_]\w*[ ]*:[ ]*)?(BLOCK|CRITICAL)(?!\w)", I)
     END_BLOCK: Pattern = compile(r"BLOCK|CRITICAL", I)
     DO: Pattern = compile(r"[ ]*(?:[a-z_]\w*[ ]*:[ ]*)?DO([ ]+[0-9]*|$)", I)
     END_DO: Pattern = compile(r"DO", I)