fix blank spaces not being caught in several cython file types

includes *.pyx, *.pyi, *.pyi.in, *.pyd

refs pandas-dev#21980

ci/lint.sh

@@ -49,6 +49,13 @@ if [ "$LINT" ]; then
     if [ $? -ne "0" ]; then
         RET=1
     fi
+
+    trailing_space_pyx=$(find **/*\.pyx -type f -exec egrep -l " +$" {} \;)
+    if [[ -n $trailing_space_pyx ]]
+    then
+        RET=1
+        echo $trailing_space_pyx
+    fi
     echo "Linting *.pyx DONE"
 
     echo "Linting *.pxi.in"
@@ -60,6 +67,21 @@ if [ "$LINT" ]; then
             RET=1
         fi
     done
+
+    trailing_space_pxi_in=$(find **/*\.pxi\.in -type f -exec egrep -l " +$" {} \;)
+    if [[ -n $trailing_space_pxi_in ]]
+    then
+        RET=1
+        echo $trailing_space_pxi_in
+    fi
+
+    trailing_space_pxi=$(find **/*\.pxi -type f -exec egrep -l " +$" {} \;)
+    if [[ -n $trailing_space_pxi ]]
+    then
+        RET=1
+        echo $trailing_space_pxi
+    fi
+
     echo "Linting *.pxi.in DONE"
 
     echo "Linting *.pxd"
@@ -71,6 +93,14 @@ if [ "$LINT" ]; then
             RET=1
         fi
     done
+
+    trailing_space_pyd=$(find **/*\.pyd -type f -exec egrep -l " +$" {} \;)
+    if [[ -n $trailing_space_pyd ]]
+    then
+        RET=1
+        echo $trailing_space_pyd
+    fi
+
     echo "Linting *.pxd DONE"
 
     # readability/casting: Warnings about C casting instead of C++ casting
@@ -173,7 +203,7 @@ if [ "$LINT" ]; then
         RET=1
     fi
     echo "Check for old-style classes DONE"
-    
+
     echo "Check for backticks incorrectly rendering because of missing spaces"
     grep -R --include="*.rst" -E "[a-zA-Z0-9]\`\`?[a-zA-Z0-9]" doc/source/
 

pandas/_libs/tslibs/period.pyx

@@ -1538,7 +1538,7 @@ cdef class _Period(object):
         See Also
         --------
         Period.year : Return the calendar year of the period.
-        
+
         Examples
         --------
         If the natural and fiscal year are the same, `qyear` and `year` will