Don't render image heights explicitly

The CSS itself will take care of scaling the image height based on the
width. We still need to know the height to fetch the image because the
height is in the URL, but we don't need to render it in the HTML.

spec/components/page_content_spec.cr

@@ -90,7 +90,7 @@ describe PageContent do
   it "renders a figure and figure caption" do
     page = Page.new(nodes: [
       Figure.new(children: [
-        Image.new(src: "image.png", originalWidth: 100, originalHeight: 100),
+        Image.new(src: "image.png", originalWidth: 100, originalHeight: 200),
         FigureCaption.new(children: [
           Text.new("A caption"),
         ] of Child),
@@ -101,7 +101,7 @@ describe PageContent do
 
     html.should eq stripped_html <<-HTML
       <figure>
-        <img src="https://cdn-images-1.medium.com/fit/c/100/100/image.png" width="100" height="100">
+        <img src="https://cdn-images-1.medium.com/fit/c/100/200/image.png" width="100">
         <figcaption>A caption</figcaption>
       </figure>
     HTML
@@ -134,7 +134,7 @@ describe PageContent do
   it "renders an image" do
     page = Page.new(nodes: [
       Paragraph.new(children: [
-        Image.new(src: "image.png", originalWidth: 100, originalHeight: 100),
+        Image.new(src: "image.png", originalWidth: 100, originalHeight: 200),
       ] of Child),
     ] of Child)
 
@@ -142,7 +142,7 @@ describe PageContent do
 
     html.should eq stripped_html <<-HTML
       <p>
-        <img src="https://cdn-images-1.medium.com/fit/c/100/100/image.png" width="100" height="100">
+        <img src="https://cdn-images-1.medium.com/fit/c/100/200/image.png" width="100">
       </p>
     HTML
   end

src/components/page_content.cr

@@ -63,7 +63,7 @@ class PageContent < BaseComponent
   end
 
   def render_child(child : Image)
-    img src: child.src, width: child.width, height: child.height
+    img src: child.src, width: child.width
   end
 
   def render_child(node : ListItem)