Fix safe Style/ColonMethodCall offenses

Caxlsx is using both `.` and `::`, 220 occurrences vs 280 to invoke
methods on `Axlsx` module.

This commit standardizes the approach towards `.`, which will also allow
shorter lines.

Performance is not affected

```
Comparison:
      Axlsx.validate:  8515252.3 i/s
     Axlsx::validate:  8512863.7 i/s - same-ish: difference falls within error 
```

1 files changed, 13 insertions, 13 deletions

diff --git a/lib/axlsx/stylesheet/xf.rb b/lib/axlsx/stylesheet/xf.rb
index 45d362ca..6d4aab66 100644
--- a/lib/axlsx/stylesheet/xf.rb
+++ b/lib/axlsx/stylesheet/xf.rb
@@ -101,35 +101,35 @@ module Axlsx
     def protection=(v) DataTypeValidator.validate "Xf.protection", CellProtection, v; @protection = v end
 
     # @see numFmtId
-    def numFmtId=(v) Axlsx::validate_unsigned_int v; @numFmtId = v end
+    def numFmtId=(v) Axlsx.validate_unsigned_int v; @numFmtId = v end
 
     # @see fontId
-    def fontId=(v) Axlsx::validate_unsigned_int v; @fontId = v end
+    def fontId=(v) Axlsx.validate_unsigned_int v; @fontId = v end
     # @see fillId
-    def fillId=(v) Axlsx::validate_unsigned_int v; @fillId = v end
+    def fillId=(v) Axlsx.validate_unsigned_int v; @fillId = v end
     # @see borderId
-    def borderId=(v) Axlsx::validate_unsigned_int v; @borderId = v end
+    def borderId=(v) Axlsx.validate_unsigned_int v; @borderId = v end
     # @see xfId
-    def xfId=(v) Axlsx::validate_unsigned_int v; @xfId = v end
+    def xfId=(v) Axlsx.validate_unsigned_int v; @xfId = v end
     # @see quotePrefix
-    def quotePrefix=(v) Axlsx::validate_boolean v; @quotePrefix = v end
+    def quotePrefix=(v) Axlsx.validate_boolean v; @quotePrefix = v end
     # @see pivotButton
-    def pivotButton=(v) Axlsx::validate_boolean v; @pivotButton = v end
+    def pivotButton=(v) Axlsx.validate_boolean v; @pivotButton = v end
     # @see applyNumberFormat
-    def applyNumberFormat=(v) Axlsx::validate_boolean v; @applyNumberFormat = v end
+    def applyNumberFormat=(v) Axlsx.validate_boolean v; @applyNumberFormat = v end
     # @see applyFont
-    def applyFont=(v) Axlsx::validate_boolean v; @applyFont = v end
+    def applyFont=(v) Axlsx.validate_boolean v; @applyFont = v end
     # @see applyFill
-    def applyFill=(v) Axlsx::validate_boolean v; @applyFill = v end
+    def applyFill=(v) Axlsx.validate_boolean v; @applyFill = v end
 
     # @see applyBorder
-    def applyBorder=(v) Axlsx::validate_boolean v; @applyBorder = v end
+    def applyBorder=(v) Axlsx.validate_boolean v; @applyBorder = v end
 
     # @see applyAlignment
-    def applyAlignment=(v) Axlsx::validate_boolean v; @applyAlignment = v end
+    def applyAlignment=(v) Axlsx.validate_boolean v; @applyAlignment = v end
 
     # @see applyProtection
-    def applyProtection=(v) Axlsx::validate_boolean v; @applyProtection = v end
+    def applyProtection=(v) Axlsx.validate_boolean v; @applyProtection = v end
 
     # Serializes the object
     # @param [String] str